In 1967, the small German automaker NSU introduced what would be its final and most ambitious product: the remarkable Ro80. It was NSU’s first and last luxury car, a sophisticated, highly aerodynamic sedan powered by a Wankel rotary engine. The Ro80 survived for 10 years, generating critical acclaim and controversy in roughly equal measure. In this installment of Ate Up With Motor, we take a closer look at the turbulent and sometimes troubled history of the 1967-1977 NSU Ro80.
NSU PLAYS THE LONG SHOT
NSU was founded in 1873 in the small town of Neckarsulm, at the union of the Neckar and Sulm rivers in the German state of Baden-Württemberg. Like many early automakers, the company started off in a very different field, in this case sewing and knitting machines. (NSU was originally an acronym for Neckarsulm Strickmachinen Union, Neckarsulm Sewing Machine Co.) NSU started building motorcycles in 1901 and automobiles in 1905, followed a few years later by trucks.
Although the company produced some successful and rather sporty cars in the 1920s, the onset of the Depression led NSU to sell its automotive business to Fiat (which used the NSU-Fiat brand into the mid-1930s) and focus exclusively on motorcycles and motorbikes. It was not until the mid-1950s that NSU once again turned its attention to automobiles, introducing the NSU Prinz in 1957. While NSU had offered four- and six-cylinder cars back in the 1920s, the Prinz was a rear-engined mini-car powered by a decidedly motorcycle-like air-cooled, two-cylinder engine.
NSU introduced its first four-cylinder postwar car, the NSU Prinz 1000, at the 1964 Frankfurt auto show, but managing director Gerd Stieler von Heydekampf had already set his sights on bigger game. The West German economy had improved markedly in recent years, and buyers were graduating from mopeds and tiny bubble cars to larger and more luxurious sedans. NSU’s market share was only modest as it was. If the company didn’t evolve, its future looked gloomy.
In late 1962, NSU commenced work on a new model known internally as Typ 80. As originally conceived, it was to be in the same class as the Ford Taunus P4. Design targets were an engine output of 80 PS (79 hp, 59 kW), a weight of 800 kg (1,765 lb), and a price of 8,000 DM — about $2,000 at the contemporary exchange rate. Like the Taunus, the Typ 80 would have monocoque construction and front-wheel-drive, developed by chief engineer Ewald Praxl. The new model’s styling, meanwhile, was the responsibility of in-house designer Claus Luthe, who had joined NSU in 1956 after stints at Fiat and the bus maker Spengler.
Luthe’s design, commenced in early 1963 and completed as a full-size model that September, was exceptionally clean and airy, with a large, six-light greenhouse that made the car look smaller than it actually was. Space utilization was excellent, but the Typ 80 was far less boxy than most contemporary German sedans, leading to (unfounded) rumors in later years that it was actually designed in Italy like NSU’s earlier, Bertone-styled Sport Prinz coupe. The Typ 80’s most impressive attributes were its aerodynamics; in the interests of maximizing fuel economy, low drag was an important part of the design brief. Subsequent wind tunnel tests at Stuttgart Polytechnic Institute revealed a drag coefficient of 0.355, outstanding for the era.
The full-size model, which was presented to NSU’s managing board in May 1964, was very close to the eventual production model in shape, but not dimensions. After considering the car’s likely cost, Von Heydekampf and the board selected a loftier target than the Taunus: the executive car market occupied by the likes of the Mercedes W110 (200/230) and BMW Neue Klasse sedans. To compete in that segment, the Typ 80 would be scaled up in size, weight, and price, the latter eventually rising from 8,000 to more than 14,000 DM (about $3,500).
You’ll note that we haven’t yet said a word about the Typ 80’s most significant and unusual feature, its rotary engine. However, even with a completely conventional powertrain, the Typ 80 would have been a very ambitious step for NSU, analogous to Honda proceeding directly from the original 1972 Civic to the six-cylinder Legend. BMW, of course, had developed its Neue Klasse sedans after several years of focusing on motorcycles and mini-cars, but BMW had also built larger, more prestigious cars like the 502, 503, and 507 throughout the fifties and early sixties (albeit not in large numbers). By contrast, NSU hadn’t built anything like a luxury car in more than 30 years.
Moving the project so far upmarket would have been a gamble no matter what, but what elevated it from bold marketing move to Citroën-like cliff-diving audacity was the Typ 80’s intended engine, NSU’s greatest and riskiest asset: the brainchild of inventor Felix Wankel.
We talked about the development and workings of the Wankel rotary engine in last year’s article on the early Mazda rotaries, but here is a recap for those joining us late.
Inventor Felix Wankel conceived the rotary engine while still a teenager and began filing patents on such engine designs in the 1930s, but his work on the rotary was interrupted by other projects and by the war. In 1936, Wankel joined the Deutschen Versuchsanstalt Für Luftfahrt (German Experimental Institute for Aviation), designing rotary valves for Daimler-Benz’s DB601, a 33.4-liter (2,020 cu. in.) V-12 for military aircraft, and later the Junkers KM8 torpedo engine. After the German surrender, Wankel spent time in prison for his military work, but he was released in 1946 and eventually allowed to return to practical research, establishing a new shop in Lindau, Bavaria.
Shortly afterward, Wankel’s old acquaintance Wilhelm Keppler arranged an introduction to Victor Frankenberger, NSU’s technical director, and NSU research chief Walter Fröde. On Fröde’s recommendation, NSU signed a consulting agreement with Wankel, first to apply Wankel’s rotary valve concept to motorcycle engines and subsequently to develop a unique rotary supercharger.
Throughout his consulting work, Wankel tried repeatedly to convince Von Heydekampf and the NSU board to fund the development of a rotary engine. However, NSU was far from over-capitalized, so it took three years and a great deal of cajoling before the board finally agreed.
Almost as soon as Wankel’s first DKM 54 (DKM for Drehkohlbenmotor, “Rotary Piston Engine”) prototype was running, Fröde concluded that it was hopelessly impractical for anything except perhaps stationary applications. Fröde and his staff in Neckarsulm soon developed an alternative design, the KKM (Kreiskolbenmotor, roughly, “Circuit Piston Engine”), which first ran on a test stand in 1958. Unlike Wankel’s DKM, in which both the rotor and the housing rotated around a stationary shaft, the KKM used a trochoidal rotor (shaped something like a three-lobed peanut) that traced a mathematically complex path along a cocoon-shaped stationary housing.
Wankel considered the KKM a bastardization of his concept, and Fröde’s design did sacrifice a measure of the DKM’s smoothness and exceptional rev potential, but the KKM was unarguably more useful. With much of NSU’s limited capital tied up in the launch of the Prinz, the entire project was hanging by a thread, and the board was definitely not willing to foot the bill for two engines, so Fröde finally convinced Wankel to accept the KKM. (It probably helped that the deal Wankel’s business partner Ernst Hutzenlaub struck with NSU later that year ensured that Wankel would share in the patent royalties either way. In fact, Wankel and Hutzenlaub received a substantial cut — initially 40% — of NSU’s rotary engine revenues, paid through a holding company called Wankel GmbH.)
Although NSU began selling patent licenses almost immediately, beginning that fall with a deal with the aviation company Curtiss-Wright, the KKM had a long way to go before it would be a viable production engine. Fuel and oil consumption were inherently high; low-end torque was poor; and early engines suffered a host of serious maladies, including excessive exhaust smoke, seized bearings, heat-induced cracks around the spark plugs, and scored rotor housings (the infamous “chatter marks” that would also plague Toyo Kogyo’s development efforts). Probably the greatest challenge was the apex seals at the rotor tips, which were responsible for maintaining compression and preventing exhaust gases from mixing with the intake charge. Developing workable apex seals would be a major test for every user of the Wankel KKM design, including NSU itself.
In 1959, NSU developed the KKM 250, a larger version of Fröde’s initial KKM 125 that produced roughly as much power as NSU’s contemporary 583 cc (36 cu. in.) piston engine. The following year, the company installed a KKM 250 in a Prinz sedan and allowed journalists from German automotive publications to try it. This was followed months later by a Sport Prinz fitted with a further refined, more powerful 386 cc (24 cu. in.) KKM 400.
Both of these test mules were crude, but they helped to establish the Wankel engine as a viable prospect — important to the ongoing sales of patent licenses (NSU’s major source of development money) and the company’s relationship with its understandably nervous shareholders.
At the Frankfurt International Auto Show in the fall of 1963, NSU unveiled its first rotary-powered production car, the NSU Wankel Spider. The Spider was just what journalists who had driven the earlier prototypes expected of a Wankel-powered NSU: a ragtop conversion of the Sport Prinz coupe with a radiator stuffed under the bonnet to cool the rear-mounted 498 cc (30 cu. in.) KKM 502 engine. Fitted with a single two-throat Solex carburetor, the KKM 502 had 50 PS DIN (37 kW) and 52 lb-ft (71 N-m) of torque, about 15% more than the 996 cc (61 cu. in.) OHC four then being prepared for the new Prinz 1000. The price tag was DM 8,500, equivalent to about $2,125 at the contemporary exchange rate.
The Spider was not sold in large numbers, but it gave NSU useful field experience with the new engine. That was fortunate because the rotary still had significant issues. To prevent cracking around the spark plug, the rotor housing was aluminum, which was chrome-plated for hardness. Because using durable materials like cast iron for the apex seals would score the chrome surface, NSU (like Toyo Kogyo) opted for carbon seals, which had a relatively short life. When the apex seals became too worn, the engine would lose power, requiring a complete teardown to replace the seals. Oil consumption also remained high, although NSU tried to soften the blow by saying the engine’s oil use obviated the need for periodic changes; the manual recommended simply topping off the oil supply as needed.
The Wankel Spider demonstrated that the rotary did work as an automotive engine, but the KKM 502’s practical lifespan was still short and its real-world behavior left much to be desired. For a moderately priced, low-volume sports car, such deficiencies might be excusable (reliability was not the strong suit of most contemporary sports cars, even ones with perfectly conventional engineering), but expectations were different in the executive class in which the Typ 80 was expected to compete.
Nonetheless, NSU was now committed. When the four-cylinder Prinz 1000 debuted at Frankfurt in 1964, Von Heydekampf announced that NSU’s future engine development would focus exclusively on the Wankel.
TYP 80 TO RO80
NSU announced the production version of the Typ 80 in early 1965. After considering and discarding a variety of possible names (mostly for trademark reasons), NSU christened the new model Ro80, “Ro” for Rotary, “80” for the type number.
At that time, the Ro80 was still in the relatively early stages of its development. Final wind tunnel testing did not take place until September of that year and road testing of early prototypes didn’t begin until the following spring. It should be remembered that the Ro80 was a genuinely all-new design that shared very little with NSU’s other models, all of which (save the Spider) had rear-mounted, air-cooled engines. The Ro80 was considerably more sophisticated than the Prinz or Sport Prinz, featuring not only front-wheel drive but also power-assisted ZF rack-and-pinion steering, fully independent suspension (MacPherson struts in front, semi-trailing arms and coil springs in back), and ATE-Dunlop disc brakes all around (mounted inboard at the front) with a proportioning valve to limit rear-wheel lockup.
The Ro80 was initially slated to use a two-rotor version of the KKM 502 used in the Wankel Spider, but ongoing issues with the Spider’s seals led to the development of the extensively redesigned KKM 612, also of 995 cc (61 cu. in.) swept volume, but trading the rotor housing’s previous chrome plating for a new ElNiSil (electrodeposited nickel-silicon carbide) coating, developed by MAHLE GmbH under the trademark Nikasil. (It has subsequently seen widespread use as a coating for aluminum pistons and later aluminum cylinder bores for reciprocating engines.) The KKM 612 engine also used cast iron apex seals, which NSU hoped would wear better and have better detonation resistance than the Spider’s carbon seals while greatly reducing frictional losses. (See the sidebar on the following page.)
Like the early Mazda rotary engines, the KKM 612 had dual ignition coils and two spark plugs per chamber, giving a total of four; both plugs were set to fire simultaneously. With two Solex 18/32 HHD two-throat carburetors, the KKM 612’s output was 115 PS DIN (85 kW) and 117 lb-ft (159 N-m) of torque, more than twice the output of the Spider’s single-rotor engine. For all that, the two-rotor engine was very compact and quite light, with a dry weight of only 265 lb (120 kg). (Mazda’s contemporary 982 cc (60 cu. in.) L10A engine, with side intake ports, was lighter still, but had only 110 PS (81 kW) and 96 lb-ft (130 N-m) of torque.)
While the two-rotor engine was considerably more powerful than the Typ 80’s original specification, the Ro80’s weight had also risen by more than 50%, which also raised new questions about what transmission the car should use. NSU had considered using an unusual hydrostatic transmission, but concluded that it was not sufficiently refined for production. A conventional four-speed gearbox also proved less than satisfactory because it highlighted a weakness of the KKM engine’s peripheral intake ports: an annoying driveline ‘snatch’ on the overrun (i.e., with the throttle closed and the clutch engaged, allowing the engine to be driven by the car’s momentum rather than the other way around), caused by exhaust gas being drawn back into the intake charge. A fully automatic transmission would have avoided that problem, but was apparently ruled out because it would have sapped too much engine power.
The alternative NSU finally chose was the three-speed Saxomat, a semi-automatic transmission made by Fitchel & Sachs, similar to the four-speed Sportomatic unit then used by Porsche. The Saxomat transmission was essentially a fully synchronized three-speed manual gearbox (with an overdrive top gear) with both a dry-plate clutch and a torque converter that shared the engine’s oil supply. The plate clutch was operated by a vacuum servo, controlled by a switch in the top of the shift lever; simply touching the gearshift knob would disengage the clutch.
The Saxomat transmission offered two major advantages for the Ro80. First, the torque converter largely eliminated the overrun snatch because there was no direct mechanical connection between engine and gearbox; the gearbox input shaft was driven by the converter turbine. Second, the converter’s additional low-speed torque multiplication (2.3:1 at stall) helped to compensate for the Wankel’s mediocre low-end torque and reduced the need to shift in gentle driving.
The Ro80 was a very promising package, but it represented a great deal of new ground for NSU, and there were serious questions about whether the car was ready for public consumption. According to writer Dieter Renkin, Ewald Praxl asked Von Heydekampf for more time for testing prior to series production, but by the time pilot production began in August 1967, NSU’s back was against the wall. NSU’s existing cars were selling reasonably well (more than 100,000 units in both 1966 and 1967), but the company was no longer in the motorbike business and had invested nearly all of its available resources in the Ro80 and the follow-on Typ 70 (a smaller piston-engined car intended to debut at the 1969 Geneva show as NSU’s answer to the BMW 1600/1602). That fall, Von Heydekampf freely admitted to the press that NSU was betting everything on the Ro80. The company simply couldn’t afford to wait any longer for launch.
THE NSU RO80 DEBUTS
The new car made its public debut at the Frankfurt show in September 1967. The NSU Ro80 was not the world’s first two-rotor production car — that honor went to the Mazda Cosmo Sport, which went sale earlier that year, two and a half years after it bowed at the 1964 Tokyo Motor Show — but the NSU was the first rotary-powered production sedan, arriving about two months before the public introduction of Mazda’s Familia Rotary Coupé (R100). The Ro80 went on sale shortly afterward with a starting price of 14,150 DM (about $3,550), raised a nominal 40 DM ($10) in early 1968. That price put the Ro80 a full 1,000 DM (about $250) above a Mercedes 230 sedan and almost 2,300 DM ($580) more than a six-cylinder Opel Commodore — an ambitious price tag indeed.
Even without the rotary engine, the Ro80 would have been a great achievement. The aerodynamics were probably the best of any contemporary production car; only the Porsche 911 and Citroën DS21 even came close. The Ro80’s chassis was also superb. Despite its skinny Michelin tires, the combination of wide track, low center of gravity, and fine steering made for excellent handling. The ride was outstanding as well, thanks to long wheel travel, well-tuned spring and damping rates, and low unsprung weight.
As was typical for German luxury cars, the Ro80’s interior did not approach American, British, or French standards of plushness, but it was tasteful, roomy, and well-made. The body had a reassuring sense of solidity, and assembly quality was high. There were nits that could be picked — the labeling of minor controls was rather cryptic (resolved in 1970), the seats needed more lateral support (ditto), and the ventilation system would have benefited greatly from an interior fan — but the Ro80 was nonetheless genuinely impressive, particularly considering it was NSU’s first executive car.
Much of the press attention, of course, focused on the Ro80’s powertrain, which drew considerable interest and mixed reviews. The free-revving nature and smoothness of the rotary engine elicited much praise, but while the engine’s power output compared favorably with that of a 2-liter (122 cu. in.) carbureted piston engine, torque was meager below about 3,000 rpm. The torque converter helped a bit, but the Ro80 had widely spaced gears and around 2,850 lb (1,290 kg) of curb weight, which made for sleepy low-speed performance, particularly if one followed NSU’s suggestion to leave the transmission in second for most city driving. Most testers reported 0-60 mph (0-97 km/h) times of around 14 seconds through the gears. While brake-torquing (revving the engine against the brake in neutral at launch) could trim a second or so off that time, the Ro80 was not well-suited for drag strip starts. The Saxomat transmission wasn’t much help in that regard; achieving smooth shifts took practice, and some testers found that fast changes could beat the synchros.
The Ro80 came into its own at autobahn speeds, where the relatively short overall gearing (3,200 rpm at 60 mph (97 km/h) in top) put the engine into a richer part of its torque curve, providing much brighter acceleration and snappy passing response. The rotary remained uncannily smooth all the way to redline, and with the well-suppressed wind and road noise, drivers were well-advised to keep a close eye on the (rather optimistic) speedometer. Claimed top speed was about 112 mph (180 km/h), a respectable figure for the Ro80’s size and price, and very few cars of the time were as stable or comfortable at high speeds.
Even in relatively brief road tests, the NSU rotary engine displayed a few disagreeable habits, including recalcitrant cold starting, but the biggest complaint was fuel economy. On an absolute scale, the Ro80’s fuel consumption was not disastrous for the era, ranging from 13 to 18 mpg (U.S.; 18 to 13 L/100 km) depending on conditions, and it was actually better at high speeds than many piston-engined rivals. However, the bottom line was that the KKM 612 was a 995 cc (61 cu. in.) engine with fuel economy comparable to a 4,235 cc (258 cu. in.) Jaguar.
Added to the rotary engine’s prodigious appetite for oil and spark plugs, such consumption made the NSU Ro80 rather expensive to run for European buyers. (In that, it was probably fortunate that the Ro80 was not in the Taunus/Cortina class, where the rotary engine’s thirst would have been an even greater marketing problem.) One consolation was that, as with the Wankel Spider, the Ro80 did not require routine oil changes, although it was imperative to keep the oil supply full.
Still, the new model made a good first impression, and its combination of merit and novelty earned it the European Car of the Year award. Initial 1967–68 sales totaled around 6,400 units — not bad for the price, particularly considering that right-hand-drive models were not available until the fall of 1968 and the Ro80 was not certified for U.S. emissions standards until mid-December 1969.
THE TROUBLE BEGINS
The NSU Ro80 was an entirely new product from a company that hadn’t sold an executive car in conscious memory, powered by a bleeding-edge engine, and rushed into production with less testing than its designers would have preferred. What could possibly go wrong? In all fairness, if we discount the engine, the answer is “Surprisingly little”; even the curious Saxomat transmission was generally reliable. The Wankelmotor, however, quickly established itself as a problem child, threatening to overshadow the Ro80’s other virtues.
Despite the rotary engine’s apparent simplicity, long-term testers soon complained that the KKM 612 could be frustratingly difficult to keep in proper tune. If the twin Solex carburetors were even slightly out of adjustment, the result would be hesitation and flat spots, which took a fine touch to correct. The spark plugs were another headache; the rotary had a unique flair for fouling its plugs in slow driving. The plugs’ position in the combustion chamber made it impossible to clear them with a burst of speed as one could with a piston engine, so the only recourse was to remove the plugs and clean or replace them. If the car were driven mostly on open roads, that was not a major concern, but regular urban commuting limited plug life to 5,000 miles (8,000 km) or less, and the specified plugs were very expensive, 10 to 12 times the cost of a standard spark plug.
Those shortcomings were tolerable, if annoying, but they were followed by a rash of more serious engine problems, including failure of the apex seals and/or eccentric shaft bearings, often at less than 25,000 miles (40,000 km). Rather than attempting to repair or rebuild those engines, NSU generally opted to replace them (sometimes more than once) under and sometimes beyond the 20,000-mile (32,000-km) factory warranty. That was inevitably very expensive, and while NSU’s rather generous engine replacement policy was intended to appease nervous or angry customers, it actually served to drag down the car’s reputation.
The root of the problem (aside from the Ro80’s overly hasty development) was that NSU had misjudged its customers’ real-world driving habits. The company apparently assumed that because the Ro80 was a large and thirsty car, most owners would use it in a relatively sedate fashion, mainly for long trips. In practice, the Wankel’s eagerness to rev encouraged owners to drive far more aggressively, with frequent excursions to or beyond the 6,500 rpm limit. While the engine was so smooth that it would exceed its redline without apparent complaint, such treatment exposed the limitations of the oil system, eventually leading to bearing damage. Stop-and-go driving, meanwhile, not only fouled the plugs, but also played hob with the engine’s clever three-piece, self-adjusting apex seals, particularly with liberal use of the manual choke.
While NSU subsequently made changes that at least mitigated the Ro80’s major weaknesses, the damage to the car’s image and the company’s bank account was considerable. NSU was already overextended and the Ro80’s massive warranty costs only made a bad situation worse. The ultimate price would be the company’s fiercely guarded independence.
One of NSU’s ongoing challenges was that while Wankel licensing was a crucial source of revenue, the company was not unlike a minnow trying to do business with whales. The rotary engine had obvious value, but it undoubtedly occurred to some of NSU’s larger prospective licensees that it might be simpler to absorb the whole company and its patents rather than pay royalties. Von Heydekampf, however, had always refused to be intimidated, adopting a take-it-or-leave-it attitude toward negotiations. The NSU board strenuously resisted any attempts at outside takeovers, although Citroën did acquire about 10% of NSU through the two companies’ Comobil and Comotor joint ventures (a share acquired in 1968 by Fiat).
By early 1969, however, NSU’s position was becoming untenable, so Von Heydekampf reluctantly entered discussions with Kurt Lotz, the new managing director of Volkswagen. Lotz, who had succeeded VW’s conservative Heinz Nordhoff in the spring of 1968, was still looking for Volkswagen’s post-Beetle direction and was very interested in expanding Volkswagen’s product range and production capacity. NSU needed capital very badly, but the Neckarsulm firm was still very reluctant to sacrifice any of its independence.
The compromise Lotz eventually struck with NSU was to arrange a merger with Auto Union (Audi), the Ingolstadt automaker in which VW had acquired a controlling interest back in 1964. The deal promised greater autonomy for NSU and did not require the approval of Volkswagen’s supervisory board, with which Lotz seldom saw eye to eye for various political reasons.
The merger, announced in March 1969, created a new company, Audi-NSU-Auto Union, chaired by Von Heydekampf and initially holding just under 60% of NSU stock. While a majority of NSU stockholders approved the deal, a small but vocal minority strenuously opposed it, and German law allowed those minority shareholders to demand significant concessions. Among these was an agreement providing Genussscheine, profit shares, to NSU stockholders, giving them a substantial percentage (initially 40%, subsequently raised to almost 70%) of the company’s revenues from the Wankel engine for the next decade. Another concession was that Volkswagen would not be able to use the rotary engine in its own products without paying license fees to Audi-NSU-Auto Union.
In the short term, Lotz was more interested in NSU’s piston-engined Typ 70, which had been delayed and then briefly canceled around the time of the merger, first for lack of funds and then because the car would have competed directly with Volkswagen and Audi products, including the Audi 100. Lotz decided to resurrect the project and transfer it to Volkswagen, albeit with many ostensibly minor revisions that ultimately cost nearly twice as much as NSU had spent developing the car in the first place. It was launched in the fall of 1970 as the Volkswagen K70.
That move added to the displeasure of the minority stockholders, who were already infuriated by many provisions of the merger agreement, most particularly the rather modest option price set for NSU’s remaining stock. Led by the Israeli British Bank, the minority shareholders eventually took the matter to court, an acrimonious case not fully resolved until 1971, around the time Kurt Lotz resigned. NSU may have ended up in the belly of the whale — Audi, and by extension Volkswagen — but it left the whale with a certain amount of indigestion.
Following the merger with Audi, NSU continued developing the Wankel engine and working to resolve the Ro80’s problems. In the fall of 1969, the Ro80 received a new and much cheaper transistorized ignition system with a single coil and one spark plug per chamber, along with an improved apex seal design. The latter was only an interim measure, followed in mid-1970 by a thorough update of the initial three-piece design using Ferro-TiC seals that NSU claimed were an order of magnitude more durable than the originals.
At the same time, the oil system was revised to provide better protection for the eccentric shaft bearings at high rpm, supplemented a year later by a dashboard buzzer to warn of over-revving. An automatic choke was added in 1972, and for 1973, the twin carburetors gave way to a single two-throat Solex 32DTI TS; output increased slightly, to 117 PS DIN (115 hp, 86 kW) and 122 lb-ft (165 N-m) of torque. All cars now had emissions controls, including a thermal reactor similar to that used by Mazda, but NSU had never had much of a U.S. presence and we doubt that many Ro80s were formally imported after about 1970. NSU had almost certainly exited the American market by the 1973 model year, as the Ro80 did not meet the new U.S. 5 mph (8 km/h) bumper standards.
Those changes made the Ro80 much more reliable than it had been (if still not wholly trouble-free), although its appetite for fuel, oil, and spark plugs had not abated. However, it was not easy to overcome the Ro80’s bad reputation, particularly with the alarming reports in the press and editorial cartoons in German magazines showing NSU drivers greeting each other with hand signals to indicate how many engines their car had had (a practice many English-language histories subsequently reported as fact). Sales for 1970 were down nearly 20% from the Ro80’s 1969 peak and 1971 sales fell a further 50%.
Business rallied in 1972 and 1973, but with the Wankel’s considerable thirst, the OPEC embargo in late 1973 and early 1974 proved crippling. An NSU Ro80 was already an expensive car to run, and fuel shortages made its sales a very difficult proposition in Europe. Production dropped to fewer than 1,200 units in 1974 and about 1,800 in 1975. Constant price escalation probably didn’t help: the list price in Germany climbed from just under 18,000 DM (about $6,800) in the spring of 1973 to nearly 20,000 DM (about $7,700) by the fall of 1974. By mid-1975, the Ro80 had also disappeared from the U.K. except by special order.
By then, NSU’s piston-engined cars were all dead, replaced on the assembly lines by Audi products. The K70’s days were numbered: Its execution had been flawed, its performance was disappointing, and being sold as a Volkswagen meant that NSU’s original plan to offer it with a rotary engine (perhaps as an answer to the BMW 2002) never came to fruition. The K70 finally died in May 1975, having sold around 211,000 units.
The joint ventures between NSU and Citroën also came to nothing. The sole product of the Comobil venture was the Citroën M35 (essentially an Ami 8 with a single-rotor Wankel engine), a road-going research project of which only a few hundred were built. Comotor’s two-rotor KKM 622 engine (derived from the Ro80’s KKM 612) was a costly flop, used only in the ill-fated Birotor version of the Citroën GS, and plans to sell the engine to other automakers never materialized.
Despite all that, the NSU Ro80 was not dead. It received more changes in mid-1975, including new taillights and new bumpers, and in 1977, the Saxomat transmission received new internal gear ratios. The latter modification foreshadowed Audi-NSU’s ambitions for a second-generation Ro80, something that had been rumored in the press for several years. The new Ro80 was to feature a larger, more powerful engine with a geometric displacement of about 1,500 cc (92 cu. in.), aimed at six-cylinder piston-engined rivals.
NSU’s original plans were for the new Ro80 to use a three-rotor version of the KKM 612 engine, the KKM 619, giving a total displacement of 1,493 cc (91 cu. in.). Further investigation suggested that it would be easier and cheaper to create a new two-rotor engine using a larger rotor diameter to give the same 1,493 cc swept volume. The result was the KKM 871 (known as EA871 in Audi/Volkswagen parlance), which was good for 170 to 180 PS (125 to 132 kW) in preproduction form. The big engine, prototypes of which were tested in Audi 100 development mules, provided much better performance than the smaller KKM 612 and attracted interest from a number of other automakers. Two EA871A engines, de-rated to 150 PS (110 kW), even found their way into prototypes of the RFP Fanliner, a small acrobatic aircraft.
While the EA871 project enjoyed some support within NSU-Audi — leading to plans to use the new engine in the new C2-platform Audi 100/200 as well as a new Ro80 — technical director Ferdinand Piëch was increasingly skeptical about the Wankel’s viability in the European market. Piëch believed that diesel was a better bet than the rotary, which still suffered from relatively poor thermal efficiency and inherently heavy fuel consumption. (Based on the SAE thermal equivalency formula, the EA871 would have been comparable to a 4.5-liter (273 cu. in.) piston engine, and probably very thirsty by European standards.) Although Piëch eventually succeeded in ending Wankel development, it was not a universally popular decision. According to writer Martin Buckley, some senior company executives continued to favor cars powered by preproduction EA871 engines well into the 1980s. A few EA871 engines later found their way into private hands.
With its successor canceled, the NSU Ro80 expired in the spring of 1977, the final car leaving the assembly line on April 19. It was the last NSU production car, although NSU remained part of the corporate name until the mid-1980s and the marque is still owned by Volkswagen AG.
Ro80 production totals differ somewhat from source to source, but the most common figure is 37,402. (Some sources list 37,240, which makes us suspect that one or the other of these figures is actually a typographical error; your guess is as good as ours as to which!) Where most accounts agree is that the Ro80 was never profitable for either NSU or Audi. Even with lower warranty costs, it’s hard to see the car as a money-maker at such a low volume, despite a price that by the end of production had climbed to 23,620 DM (equivalent to more than $10,000).
While the production Audi C2 (1976–1982 Audi 100/200/5000) never received the planned rotary engine, the C2 and subsequent C3 had a lot in common with the NSU Ro80 — and not just because stylist Claus Luthe was Audi’s design director during the C2’s development (although he’s generally credited only with the interior; the exterior was the work of Hartmut Warkuß). The Audi lacked the Ro80’s semiautomatic transmission, independent rear suspension, and inboard front brakes, and only the more expensive Audi 200 had rear discs, but in overall size, profile, ride and handling balance, and concern with aerodynamics, the Audi seemed to have studied at the feet of its NSU predecessor. (It’s also easy to see how the Audi 200 could have been the basis of a next-generation Ro80.) Although the NSU Ro80 remains obscure in the U.S., its Audi descendants had a strong influence on automotive design throughout the 1980s and 1990s, in America and Japan as well as in Europe.
With its groundbreaking design and unusual powertrain, it’s tempting to characterize the NSU Ro80 as a car ahead of its time. In some ways that was true, but in others, the future the Ro80 presaged was not ours. The Ro80 was a car designed for an alternate world of light traffic, unrestricted Autobahnen, and moderately priced regular gasoline. For such conditions, the KKM 612 and Saxomat were a fine combination, superior in many respects to contemporary petrol and diesel reciprocating alternatives. However, by the mid-seventies, such a world was purely a fantasy for most drivers. The reality was gridlock, speed limits, and soaring fuel prices, an environment for which the Wankelmotor was considerably less than ideal.
Doubts about the Wankel’s reliability dogged the NSU Ro80 for many years, and the car’s rehabilitation (in the Soviet sense) was a lengthy process. A reputation for early engine failure does nothing good for residuals, so it’s little surprise that the Ro80’s resale values plummeted catastrophically in the 1970s. Since the rest of the car was generally quite sound, some owners resorted to engine swaps. A popular choice was the German Ford V-4, which rivaled the KKM 612 for compactness, if not power or refinement. Another obvious substitution was a two-rotor Mazda 12A or 13B; while many surviving Ro80s once again have rotary engines, not all were made in Neckarsulm.
Felix Wankel eventually sold his stake in the engine that bore his name: In the early seventies, he and Ernst Hutzenlaub sold Wankel GmbH to Roland Rowland’s Lonrho for a reported 64 million DM (about $25 million). Wankel’s lab in Lindau closed a few years later, after Wankel GmbH was sold again to Dankwert Eiermann and Jürgan Bax. By then, the auto industry’s interest in the rotary engine was rapidly fading. Development for nonautomotive applications like light aircraft continued into the 21st century, but by the time Felix Wankel died in 1988, Mazda was the last holdout in the auto industry. With the production of the final Mazda RENESIS engine in June 2012, the rotary engine’s passenger car career appears to be over unless Mazda is able to revive its currently inactive 16-X project.
Back in 1956, before the NSU KKM was even invented, Ford Motor Company engineer Donald Frey (quoted a decade later in Motor Trend) opined that for a new engine design to seriously challenge the dominant four-stroke reciprocating (Otto-cycle) format, it was not enough to beat the Otto cycle in a few areas — the newcomer had to be superior in all or most respects. The rotary engine came closer than many challengers, but the Otto-cycle engine was able to close the gap in many of the Wankel’s areas of superiority faster than the Wankel’s limitations could be overcome.
Much the same could be said of the NSU Ro80. It went head to head with some of the toughest competitors in the business and acquitted itself far better than anyone really had a right to expect, but while the Ro80 was good enough to challenge the dominant players, it didn’t have enough of an edge to unseat them. By the time the bugs had been worked out, NSU’s rivals had improved too, leaving the Ro80 as the brave but risky alternative.
Would the Ro80 have been more successful if NSU had opted for a more orthodox design brief, perhaps with the alternative of a conventional piston engine? Maybe, maybe not, but one thing is certain: The results would have been far less interesting.
The author would like to thank Jim Sykes and Andrew Buc for their generous assistance and the use of their photos. (In the interests of full disclosure, Andrew has previously made financial contributions to Ate Up With Motor, albeit not specifically in connection with this or any other individual article.)
Our sources on the history of NSU, the Wankel engine, and the Ro80 included: “2 Car Test: Citroën ID20, NSU Ro80,” Autocar 1 May 1969, reprinted in NSU Ro80: A Brooklands ‘Road Test’ Limited Edition, ed. R.M. Clarke (Cobham, England: Brooklands Books, Ltd., 1999), pp. 36-41; R.F. Ansdale, “Wankel Progress,” Motor Trend Vol. 18, No. 2 (February 1966), pp. 29-31; “Audi 100 C2,” Unique Cars and Parts, www.uniquecarsandparts. com.au, accessed 15 August 2012; the Auto Editors of Consumer Guide, “1963-1966 NSU Wankel Spider,” HowStuffWorks.com, 24 July 2007, www.howstuffworks. com/ 1963-1966-nsu-wankel-spider.htm, accessed 7 October 2011, and “1967-1977 NSU Ro80,” HowStuffWorks.com, 29 October 2007, auto.howstuffworks.com/1967-1977-nsu-ro80.htm, accessed 7 July 2012; “Auto Test: NSU Ro80,” Autocar 13 July 1974, reprinted in NSU Ro80, pp. 71-75; Roger Bell and Anthony Curtis, “20,000 Miles on NSU Ro80,” Motor 28 September 1974, reprinted in ibid, pp. 76-79; Stuart Bladon, “Long-Term Report: NSU Ro80 Final report at 23,000 Miles,” Autocar 31 August 1972, reprinted in ibid, pp. 64-67, and “Smoky Rotaries,” Classic Car July 1987, reprinted in ibid, pp. 85-87; Griffith Borgeson, “NSU Wankel Comes of Age,” Motor Trend Vol. 19, No. 12 (December 1967), reprinted in ibid, pp. 10-13; Martin Buckley, “Brave new world,” Classic & Sports Car July 1995, reprinted in ibid, pp. 88-92; Charles Bulmer, “Serious Contender,” The Motor 9 September 1967, reprinted in ibid, pp. 5-9; “Buying Secondhand: NSU Ro80,” Autocar 26 November 1977, reprinted in ibid, pp. 82-84; “Car of the year–or decade? (Motor Road Test No. 5/68 – NSU Ro80),” The Motor 3 February 1968, reprinted in ibid, pp. 19-24; Wallace Chinitz, “Rotary Engines,” Scientific American Vol. 220, No. 2 (1969): 90–99; Richard Copping, VW Golf: Five Generations of Fun (Dorchester, Dorset: Veloce Publishing Ltd. 2006); Mike Covello, ed., Standard Catalog of Imported Cars 1946-2002, Second Edition (Iola, WI: Krause Publications, 2001); Anthony Curtis, “Classic Ro80,” Classic Cars August 1975, reprinted in NSU Ro80, pp. 80-81, and “Is cleanliness three-cornered?” New Scientist and Science Journal Vol. 49, No. 740 (25 February 1971), pp. 415-417; “Dual-Wankel coupe,” Popular Science Vol. 203, No. 2 (August 1973), p. 70; “Die Wankelmotoren von NSU,” Der Wankelmotor, 2000-2012, www.der-wankelmotor. de, accessed 13 August 2012; Jim Dunne, “Detroit Report,” Popular Science Vol. 210, No. 4 (April 1977), p. 56; J.L. Ellis and K. 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Johnson, Six Men Who Built the Modern Auto Industry (St. Paul, MN: Motorbooks/MBI Publishing, 2005); David LaChance, “Whirl Premiere,” Hemmings Sports & Exotic Car #47 (July 2009); Brian Long, RX-7: Mazda’s Rotary Engine Sports Car (Revised 2nd Edition) (Dorchester: Veloce Publishing Ltd., 2004); Karl Ludvigsen, “How Big Are Wankel Engines?” Hemmings Sports & Exotic Car April 2008; Julian Marsh, “Citroën GS Birotor,” Citroënët, 2002, www.citroenet. org.uk, accessed 21 August 2012; John Matras, Mazda RX-7 (Sports Car Color History) (Osceola, WI: MBI Publishing Company, 1994); Rob Maselko, “Feature Car: ur-TTS,” Fourtitude.com, 25 June 2007, fourtitude. com, accessed 15 August 2012; Patrick McNally, “The NSU Ro80,” Autosport 8 September 1967, reprinted in NSU Ro80, p. 14; Mazda Motor Corporation, “Mazda Spirit: The Rotary Engine,” 13 August 2007, www.mazda. com, last accessed 20 October 2011; Günther Molter, “Wankel-Powered NSU Spider,” Road & Track Vol. 16, No. 4 (December 1964), pp. 50–52; “Modern Motor road test: NSU Ro80,” Modern Motor December 1969, reprinted in NSU Ro80, pp. 48-52; Günther Molter, “NSU Ro80,” Road & Track Vol. 19, No. 2 (October 1967), reprinted in ibid, pp. 15-18; “MOTOR RACING joins the revolution,” Motor Racing, January 1969, reprinted in ibid, pp. 34-35; Jan P. Norbye, “The Front-Drive Cars in VW’s Future,” Popular Science Vol. 199, No. 4 (October 1971), pp. 10-12, “The View Down the Road,” Popular Science Vol. 206, No. 2 (February 1975), p. 52, The Wankel Engine: Design, Development, Applications, 2nd printing (Philadelphia: Chilton Book Company, 1972); and “Why Detroit Is Doing a Double Take on the Wankel,” Popular Science Vol. 198, No. 1 (January 1971), pp. 54-55, 112; “NSU-Audi,” Der WankelMotor, 2012, www.der-wankelmotor. de, accessed 13 August 2012; “NSU Wankel rotary engines and cars,” Craig’s Rotary Page, cp_www.tripod. com/rotary/ pg05.htm, accessed 13 August 2012; “NSU Wankel Spider,” NSU Prinz, 2008, www.nsuprinz. com, accessed 7 October 2011; Robert van Overbeeke, “Unilateral idealism,” GTO Magazine #6 (December 2007); Dieter Renkin, “Birth of the Ro80,” Classic & Sports Car July 1995, reprinted in NSU Ro80, pp. 92; Graham Robson and the Auto Editors of Consumer Guide, Volkswagen Chronicle (Lincolnwood, IL: Publications International Ltd., 1996); “Ro80 Reassessment,” CAR August 1970, reprinted in NSU Ro80, pp. 46-47; David Scott, “First Test: NSU’s Twin-Rotor Wankel-Powered Sedan,” Popular Science Vol. 191, No. 3 (September 1967), pp. 90-91, 203; Edoard Seidler, “Dr. Kurt Lotz: Vorstandsvorsitzender of Volkswagen: The man who thinks beyond the Bug,” Motor Trend Vol. 21, No. 8 (August 1969): 18–22, 96, and “Overseas Report: Who Wants NSU?” Motor Trend Vol. 21, No. 5 (May 1969): 46–47; “Statistische Daten,” Ro80-Club International, ro80club. org/das-auto/ statistische-daten, accessed 14 August 2012; Jason Torchinsky, “The Last Mazda Wankel Engine Has Been Built,” Jalopnik, 26 June 2012, jalopnik. com, accessed 29 June 2012; “Trail Blazer, White Elephant or Both?” CAR June 1972, reprinted in NSU Ro80, pp. 60-63; “Upheaval of an empire: How Lotz went out and Leiding came in,” Autocar 25 November 1971, pp. 44-47; Paul Van Valkenburgh, “NSU Ro80,” Sports Car Graphic October 1969, reprinted in NSU Ro80, pp. 42-45; “Volkswagen K70: Sad, unwanted child of a forced marriage,” The Independent 2 March 2004, www.independent.co. uk, accessed 23 July 2012; Christian von Klösterlein, “Claus Luthe – eine Retrospektive,” Ro80-Club International, 2008, ro80club. org, accessed 14 August 2012; “West Germany: The Wankel Wager,” TIME 8 September 1967, p. 110; “What Car? tests/NSU Ro80: Yesterday’s car of tomorrow,” What Car? October 1974, reprinted in NSU Ro80, pp. 68-70; and the Wikipedia® entries for the Audi 100 (en.wikipedia.org/wiki/Audi_100, accessed 15 August 2012), the German Audi 100 page (de.wikipedia.org/wiki/Audi_100_C2, accessed 15 August 2012), the German Audi 200 page “Audi 200” (de.wikipedia.org/wiki/Audi_200, accessed 22 August 2012), Claus Luthe (en.wikipedia.org/wiki/Claus_Luthe, accessed 7 July 2012), Felix Wankel (en.wikipedia.org/wiki/Felix_Wankel, accessed 22 August 2012), Kurt Lotz (en.wikipedia.org/wiki/Kurt_Lotz, 11 August 2012), NSU Motorenwerke (en.wikipedia.org/wiki/NSU_Motorenwerke, accessed 14 August 2012), the German NSU Prinz page (de.wikipedia.org/wiki/NSU_Prinz, accessed 23 August 2012), NSU Ro80 (en.wikipedia.org/wiki/NSU_Ro_80, accessed 7 July 2012), Rudolf Leiding, (en.wikipedia.org/wiki/Rudolf_Leiding, accessed 10 August 2012), Sulm (Germany) (en.wikipedia.org/wiki/Sulm_(Germany), last accessed 7 September 2021), and Supervisory Board (en.wikipedia.org/wiki/Supervisory_Board, 11 August 2012).
Some historical exchange rate data for the dollar, the sterling, and the Deutschmark came from Lawrence H. Officer, “Exchange Rates Between the United States Dollar and Forty-one Currencies,” MeasuringWorth, 2011, https://www.measuringworth.org/exchangeglobal/, used with permission. Exchange rate values cited in the text represent the approximate equivalence of British, German, and U.S. currency at the time, not contemporary U.S. suggested retail prices, which are cited separately. Please note that all exchange rate equivalencies cited in the text are approximate; this is an automotive history, not a treatise on currency trading or the value of money, and nothing in this article should be taken as financial advice of any kind!
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