RX-Rated: Mazda’s Early Rotary Cars, Part 1

Mazda Cosmo Sport on test track (ID 0255s) copyright 1968 Mazda
The revised Mazda Cosmo Sport on a test track (possibly at Toyo Kogyo’s own Miyoshi Proving Grounds), pursued by what looks to be a new Mazda Familia Rotary Coupé. (Photo circa 1968; copyright and courtesy Mazda)

In September, Toyo Kogyo introduced an updated Cosmo Sport known as the L10B. While engine displacement was unchanged, porting, carburetion, and intake modifications boosted the 982 cc (60 cu. in.) engine to 130 PS (128 hp, 97 kW), comparable to the Nürburgring cars. Externally, the L10B looked little different than before, but the front wheels were moved forward 5.9 inches (150 mm), increasing wheelbase to 92.5 inches (2,350 mm); overall length was actually slightly reduced. (We don’t know the rationale for the change, but it may have been an effort to improve ride quality.) Meanwhile, the gearbox acquired an overdrive fifth gear; a vacuum servo was added to the brakes; the wheels were enlarged to 15 inches (381 mm); and air conditioning was newly optional, mounted on the shelf behind the front seats.

The changes added about 110 lb (50 kg) to the Cosmo Sport’s curb weight, but with the added power, the L10B was even faster than before, with an advertised (and probably conservative) top speed of 124 mph (200 km/h). The revised Cosmo was more expensive as well, with base price rising to ¥1,580,000 (a bit under $4,400 at the contemporary exchange rate). Although the L10B was once again offered only with right-hand drive, a few were officially exported. It appears that most export models used the earlier engine and four-speed gearbox and carried the “110S” identification of the L10A cars.

1967 Mazda Cosmo Sport interior (ID 204) copyright 2007 Mazda
Despite its rocket ship exterior styling, the interior of the Mazda Cosmo Sport (here an early L10A, with four-speed gearbox) was refreshingly no-nonsense, featuring full instrumentation and somber black trim, leavened with a wood-rimmed steering wheel and then-fashionable houndstooth check upholstery. (Photo circa 2007, copyright and courtesy Mazda)

The L10B remained in limited production through the 1972 model year. The Cosmo received a bit of extra publicity in 1971, when the car was featured on the television series Return of Ultraman, and at least one Cosmo Sport was used as a highway interceptor by the Hiroshima Prefecture Police into the mid-1970s. However, the L10B was expensive for the Japanese market, and sales rarely topped 200 units a year. The final production tally was 1,176, not including the earlier L10A models.

The Cosmo Sport was an interesting exercise, but it was really only a prelude to Toyo Kogyo’s biggest gamble: the first mass-market Mazda rotary.


In November 1967, Toyo Kogyo began rolling out the second generation of its compact family car line, the Mazda Familia, originally launched in 1963–1964. The Familia was rapidly becoming the company’s volume product, and the new version was the first model slated for export in meaningful numbers. At launch, the Familia was offered only with four-cylinder piston engines, but at the Tokyo Auto Show that fall, Toyo Kogyo exhibited a rotary version of the new coupe, identified as the RX-85 and powered by a detuned version of the Cosmo Sport’s 982 cc (60 cu. in.) two-rotor engine.

1968 Mazda Familia Rotary Coupe R100 front 3q copyright 1968 Mazda
An early press photo of the 1968 Mazda Familia Rotary Coupe (officially styled “Rotary Coupé”). The rotary-engined Familia, known as R100 in some export markets, was 150.8 inches (3,830 mm) long on an 89-inch (2,260mm) wheelbase. Shipping weight was 1,775 lb (805 kg), rising to 2,010 lb (912 kg) with a full tank of fuel. (Photo circa 1968, copyright and courtesy Mazda)

The production RX-85, now dubbed Mazda Familia Rotary Coupe, arrived in July 1968. To reduce production costs, its 10A engine used cast iron side housings and traded the Cosmo Sport’s chrome-molybdenum eccentric shaft for a cheaper chrome steel unit. With revised porting and carburetor settings, output dropped to 100 PS (99 hp, 75 kW) and 98 lb-ft (132 N-m) of torque, still a healthy improvement on the 59 PS (58 hp, 43 kW) of the Familia 1200’s 1,169 cc (71 cu. in.) SOHC four. In other respects, the rotary car was very much like the Familia 1200, with a four-speed gearbox, MacPherson struts, and a live axle on semi-elliptical springs. Early production models even retained the same 10.6 U.S. gallon (40 liter) capacity as the 1200, although on later rotary Familia models, the fuel tank was enlarged to 13.2 gallons (50 liters) to compensate for the rotary engine’s greater thirst.

Starting at ¥660,000 (around $1,840), the Rotary Coupe was significantly more expensive than a piston-engined Familia, but also a great deal faster. Toyo Kogyo advertised a top speed of 112 mph (180 km/h) and 0-400 meter (approximately a quarter mile) acceleration in 16.4 seconds; 0-62 mph (0-100 km/h) times were around 11 seconds. Independent testers outside Japan found those figures somewhat optimistic, but the rotary Familia still had brisk performance, and there were few other street engines of that time that could happily run to 7,000 rpm. The trade-off was fuel economy. The Familia Rotary’s thirst was not outrageous — in the neighborhood of 20 mpg U.S. (11.8 L/100 km) overall — but it was more comparable to that of six-cylinder engines than of the small fours offered elsewhere in the line. Buyers who expected fuel consumption in line with the 10A’s geometric displacement were to be sorely disappointed, something that would become the rotary engine’s bête noire.

1971 Mazda R100 coupe dash
The well-appointed interior of a Familia/R100 Rotary Coupé. This LHD car is a 1971 U.S. model. (author photo)

1971 Mazda R100 coupe fender badge
The Mazda Familia name was not widely used overseas. Piston-engined export models were generally badged “Mazda 1200,” while the rotary versions were christened Mazda R100. (author photo)

Initial sales of the Mazda Familia Rotary Coupe were modest, amounting to only 6,925 units in 1968. In mid-1969, Toyo Kogyo added a four-door sedan, the Mazda Familia Rotary SS (presumably for “sport sedan”), with a base price of ¥638,000 (about $1,775), and began exporting the rotary models to Australia and Thailand. Sales expanded to Europe in the spring of 1970.

The Mazda Cosmo Sport’s Nürburgring exploits had apparently whetted Toyo Kogyo’s appetite for competition, because the company entered a Familia Rotary Coupe in the Singapore Grand Prix in April 1969, fitted with a 195 hp (145 kW) racing version of the 10A engine. The car won its class, the Familia Rotary’s first racing victory. Three more cars, detuned to a still-robust 187 hp (139 kW), entered the Spa-Francorchamps 24 Hour in Belgium that August, taking fifth and sixth. Those cars subsequently headed to the Nürburgring for the 1969 Marathon de la Route, but only one finished the race, taking fifth overall. A Familia Rotary Coupe, tuned for 214 hp (160 kW), won the All Japan Suzuka Automobile Race in November 1969.

The following summer, Mazda R100 coupes competed in the RAC Tourist Trophy and West Germany’s Touring Car Grand Prix before taking a second shot at the Spa-Francorchamps 24 Hour, once again coming in fifth. If not a spectacular success, the racing campaign was a credible effort, and paid dividends to later privateers. Many of the pieces developed for the competition cars subsequently became available over the counter in a series of sport kits.

Toyo Kogyo took its first steps into the U.S. market in early 1970, although early sales were limited to the Pacific Northwest. The Familia was part of the initial lineup, offered either with a conventional four-cylinder engine (as the Mazda 1200, in sedan, coupe, or wagon form) or with rotary power (as the R100 coupe). With a starting price of $2,495 POE, the American Mazda R100 was $550 more expensive than the conventionally powered Mazda 1200 coupe, which had only 64 gross horsepower (48 kW) to the R100’s 100 hp (75 kW). We have no sales breakdowns for the 1970 model year, but total U.S. sales for all Mazda cars and trucks amounted to fewer than 2,500 units. Those sales would grow spectacularly over the next three years.


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  1. I’ve always loved Mazda’s rotary cars. Fantastic article, and I can’t wait for part 2…

  2. Great story looking forward to part 2. A friend in Tasmania had several of those bertone Luces nice cars the later models had the 1800 Capella engine.

  3. Thanks for the Mazda rotary article. I’m looking forward to reading Part 2. Despite growing up around Mazda rotary-powered cars, I learned quite a bit!

  4. It’s a real shame that no one can seem to lick the engine’s fuel and oil consumption problems. I have heard some discussion of Mazda using rotaries in hybrids, which makes some sense to me. Rotaries are so small and, on paper at least, elegantly designed.

    Man, that Luce coupe is a looker.

    1. I don’t know about hybrids, but Mazda has done quite a bit of development on a hydrogen-fueled rotary, which has been offered on a limited basis for fleet sales in some markets.

      If the next-generation 16X engine materializes, Mazda is hoping to reduce fuel consumption substantially, in part by adopting direct injection. Still, since piston engines keep improving in that regard, as well, I don’t know that the rotary will ever match the reciprocating engine in specific fuel consumption. Some things can be mitigated (like wall quench), but other factors, like the combustion chamber surface area to volume ratio, are sort of the nature of the beast.

      The Luce R130 is indeed a very nice-looking car. I’d never seen one before I started researching this story.

  5. Very interesting article, well, as usual, Aaron!
    The topic was somewhat forgotten in France after Citroën heavily invested in the technology, eventually failed to make it work and had to drop the project in the early 70’s. They had been so serious about it that the models developed in the late 60’s, the GS and the XM, were designed for a rotary. They had to hastily develop a reciprocating engine for the GS and make it fit in the engine bay that was not large enough.
    The XM eventually was painfully fitted with a Peugeot engine.
    Anyway Citroën was never able to design a good engine. This huge investment and its failure played an important role in the demise of the company.


    1. “They had been so serious about it that the models developed in the late 60’s, the GS and the XM, were designed for a rotary.”
      You mean the SM, don’t you?

      1. I believe Nicolas was probably referring to the CX, which replaced the Citroën DS in 1974. I’ve never heard anything about the SM being intended for rotary power — of course the production cars had the Maserati V6 — but I think the CX was. The XM was the CX’s eventual successor, introduced in the late eighties.

  6. Right Aaron, my pen slipped, it was the CX.
    The XM was its successor.
    The SM, stangely enough, was fitted with the (in)famous Maserati V6 even though Citroën had such a faith in the future of the rotary as the ultimate replacement of the reciprocating.


    1. Timing may have had something to do with it. Citroën didn’t build the first M35 single-rotor cars until the fall of 1969, and as I understand it, they were essentially evaluation models, not yet intended for large-scale production. The BiRotor wasn’t introduced until 1974, about four years after the SM debuted. Even if Citroën were keen to give the SM rotary power, it probably wouldn’t have been ready until a few years after launch, even in a best-case scenario.

      If things had worked out differently, I imagine Citroën might have added a rotary engine to the SM later, perhaps in a second-generation version for the mid-seventies. Of course, even if the Comotor engines had been more successful, the SM was not, and might have been dropped without ever getting a rotary engine.

  7. For them the rotary was the future type of engine for all applications, just as well as they were persuaded they had a market for the SM.
    With NSU, Mazda and others working on it it’s understandable.
    Your article is very interesting by showing how Mazda made a success of it, or at least could partly make a living with it, well… that’s a success, isn’t it?
    Strangely enough it didn’t catch on as an aviation engine either.

  8. [quote=Administrator] Citroën didn’t build the first M35 single-rotor cars until the fall of 1969, and as I understand it, they were essentially evaluation models, not yet intended for large-scale production. The BiRotor wasn’t introduced until 1974, about four years after the SM debuted.[/quote]
    Starting in 69 a limited number M35, and in 73 GS Birotor, were sold to selected, faithful (and masochist) clients but the engine proved such a burden to maintain that Citroën offered to buy them back and scraped them. A few people only turned down the offer. The maintenance contracts were canceled for them. The few models still in existence are now very expensive collectors’ items, the day dream of all the GS enthusiasts.
    So there was actually a future for the rotary! ;-) As usual the car that nobody wanted became the car that nobody can afford.


    1. The source I was looking at (John Hege’s The Wankel Rotary Engine: A History) suggests that Citroën had basically intended to buy back the early evaluation engines from the outset, which would make a lot of sense.

      I don’t know about France, but in the U.S., automakers are legally obligated to provide parts support for production models for a specific period of time, typically 15 years — obviously not an appealing prospect for cars or engines that don’t end up in mass production! For that and other reasons, some automakers have tended to offer such evaluation vehicles only as a closed-end lease or other type of loan-out, with no option to actually purchase and keep the vehicle at the end; I assume that not actually selling it avoids triggering certain legal requirements.

  9. The Europeans have basically the same obligations as the Americans. As far as I understood, the deal was under specific conditions and since Citroën offered to buy them back it could cancel any support for those who rejecter the offer. It’s stupid it didn’t keep one example for history.

    Mazda is the only one who succeeded with a rotary over the years while all the others flopped.
    Well done!

  10. This is an interesting article as usual, I’m waiting for the second part. While you’re at it, how about an article covering GM’s attempt to build a rotary engine?

    1. I thought about it, but in researching this article, I’m finding that detailed information about its development seems to be surprisingly scarce. While the development of the NSU, Mazda, and Curtiss-Wright engines is pretty well-documented, GM played it very close to the vest. To really do it justice would probably require talking to some of the engineers who worked on it, assuming that the people involved are still living, and willing (and able) to talk about the program.

  11. No need to mourn it’s passing. A technological dead end. I don’t miss the
    ffffttttt exhaust “note” of them at all.
    Used to be a few about Brisbane, Delighted to see and hear that rust and enlightenment of the owners has made them almost extinct.

    Good riddence. So it could rev to 5 digits.

  12. Wow, FANTASTIC article! Thanks for the great piece on Mazda, the detail and depths you go to are above and beyond. One of the best history-of-automaker stories that I’ve read. Thanks again!

  13. Another great article Aaron. Really appreciating your narrative drive and level of scholarship. I’m starting to believe the R100/1200 body was designed by Bertone as well, but can’t verify. Do you know of any text that addresses the connections between the Italian design houses and the Japanese manufacturers in depth?

    1. I so far haven’t found anything to suggest one way or another whether the first-generation Familia was done by Bertone, although it’s certainly plausible given that Bertone did the first Luce and the Luce Rotary Coupé in that period. Even if Stilo Bertone didn’t do the Familia or the first Capella, those designs have a definite Italian flavor, much more so than subsequent products of Toyo Kogyo’s in-house design studio, which feel more typically mid-seventies Japanese.

  14. I really like that little sidebar referring how to calculate the Wankel’s full displacement. I know Japan has different regulations than the U.S. and that Mazda had no choice to only count one chamber for each rotor (Geometric Displacement) due to extra taxes being placed on “bigger” cars. Either way, I really hope Mazda brings their Wankel rotaries back to the streets, because that awesome RX-Vision concept needs to be on the roads

  15. In retrospect could the prospects of the Rotary have been slightly improved to a certain extent had Mazda and not Citroen established the Comobil later Comotor joint-ventures with NSU, where the development of the Rotary follows a more developed Mazda like trajectory instead of the engine being prematurely released as was the case with NSU and Citroen?

    Would that have been enough had it been feasible to largely butterfly away the poor reputation and resolve the issues of the early Rotary engines or would more changes have been required? Taking into consideration of course the current disadvantages of the Rotary would still remain.

    1. This is one of those “could / would /should” questions. The “could” part is straightforward, at least technologically speaking; Mazda obviously managed to keep the rotary at least reasonably viable for many years, so there’s no technical reason the fruits of their efforts couldn’t have been shared across a broader consortium.

      The “would” and “should” parts are more complicated. NSU-Wankel patent licensing agreements generally included technology-sharing provisions because NSU did not have deep pockets and figured that pooling research data would be the best way to advance the art. (Part of the reason GM’s patent license was so expensive is that GM didn’t want to participate.) Toyo Kogyo participated in that and probably contributed quite a bit to it. However, the way that knowledge was applied ended up being dictated by other factors, including a maze of different licensing agreements (like the one with Curtiss-Wright that affected distribution in North America), the concessions NSU minority stockholders wrested during the Audi merger, and the fact that the Comobil/Comotor project contributed to Citroën’s financial over-extension and eventual bankruptcy.

      Would NSU stockholders have agreed to set up such a consortium or joint venture with Toyo Kogyo? Possibly, and in that area, the progress Mazda had made with the technology might have been attractive. Would Volkswagen have been amenable to it after the NSU-Audi merger? Harder to say; I don’t imagine that Volkswagen or Audi were terribly keen on Comotor given the NSU shareholder concessions, and Toyo Kogyo being involved in that venture rather than Citroën (or succeeding Citroën) would not have changed that part of the equation. The minority shareholder deal ended up signing away most of the opportunity to profit from the rotary, and Volkswagen still wouldn’t have been in a position to use the rotary in its own products. (I don’t think Toyo Kogyo would have been in a position (financial or political) to acquire NSU instead of Volkswagen.) The main point of change in that scenario is that Toyo Kogyo by then had sunk enough money into development that they were more reluctant to simply shelve it.

      Should they have? It depends on a lot of things. If Toyo Kogyo had stepped in AFTER Citroën had been forced to bow out, the venture would have had to rebrand and might still have had a shaky image. There were customers who would have been interesting (AMC, to name one), but Mazda rotary combustion engines of the early seventies were still not without flaw, and the issues might have caused their licensees to jump ship early. (Toyo Kogyo commitment to the rotary had a lot to do with pride and the sunk-cost fallacy, to be honest.) Also, the OPEC embargo would still have really pressed the rotary’s limitations in terms of fuel consumption, which would have still hurt the project’s commercial prospects.

      So, an interesting idea, but I tend to see it coming to a similar end.

      1. Do not envision a joint-venture between NSU and Mazda in place of NSU and Citroen significantly changing things once Volkswagen acquires NSU and merges it with DKW/Auto Union to form Audi, what with the fuel crisis hurting the rotary engine’s projects in Europe. That said the NSU Ro80’s issues would have been largely butterflied away for one thing, though not sure if it would be enough for Volkswagen to actually consider a rotary model for say the 914 (as was experimented in real-life) if not a small mid-engined sportscar or some other vehicle (.

        For Citroen there is one less contributor to its financial over-extension and eventual bankruptcy, leaving only one or few more elements (e.g. Project F, possibly acquiring Maserati for V6, SM instead of DS Sport, etc) to be remedied on its end without being involved in the Comobil/Comotor project. What Citroen goes from hereon is another matter, in the absence of the French government forcing Peugeot to acquire Citroen perhaps Citroen ends up increasingly entangled with Fiat or collaborates with one and more carmakers on a few joint-ventures outside of Fiat (e.g. Alfa Romeo? Subaru? both? etc).

        Essentially the rotary engine in this scenario would be better regarded compared to real-life thanks to Mazda’s early tie up with NSU and a thorough development programme (instead of being prematurely released), yet ultimately undermined by the fuel crisis and only really considered worthwhile for sportscars.

        1. The issue pertaining to the NSU-Auto Union merger (which is explained in more detail in the Ro80 article) is that Volkswagen ended up signing away the lion’s share of Wankel-related profits and agreeing that if it used the rotary in its own products, it would have to pay license fees like any outside customer. In the short term, that was a big win for NSU minority shareholders, but it probably contributed a lot to the eventual stagnation of rotary development outside Toyo Kogyo/Mazda. On the other hand, NSU’s survival WITHOUT a merger would have been very tenuous because they had also overextended their resources with the Ro80 and what became the Volkswagen K70. Whether Toyo Kogyo would or could have afforded a merger with NSU that would have obviated the need for the Volkswagen deal I don’t know; it would have been a politically complex situation, to say the least.

          NSU was undoubtedly aware of everything Toyo Kogyo had been doing regarding rotary development, which to my understanding was a condition of the original license agreement. (I assume NSU would still have had to formally license technology subject to Toyo Kogyo patents, although I don’t think that would have been an insurmountable obstacle.) However, the problem they both faced is that each was exploring different solutions to the challenges involved (like the apex seal issue), and it wasn’t yet apparent what would work best. Toyo Kogyo didn’t attempt anything quite as daring as the NSU floating seal design (which was a brilliant idea undermined by inadequate development testing), but the differences between the earliest 12A twin-dizzy engines and the better-developed 13B found in the first-generation RX-7 are pretty substantial. It’s not that Toyo Kogyo was smarter or luckier than NSU in this regard; it’s that they kept working on it and refining their approach to factors like sealing and porting.

          However, the upshot I assume you’re getting at is that an alliance between NSU and Toyo Kogyo might have resulted in a more lasting commitment to developing the rotary engine as a commercial prospect, with a Comobil/Comotor-style entity offering engines to other companies that were interested in the technology, but either couldn’t afford or didn’t want to spend the money on developing their own. The actual reason that didn’t happen was probably mostly that Volkswagen had very limited financial incentive to bother and Citroën, as mentioned, ran out of money. If Volkswagen were not in the picture (or the settlement with the minority stockholders had turned out differently), NSU survived on its own, and Toyo Kogyo took Citroën’s place as development partner, it might be plausible.

          One other fly in the ointment with that scenario, though, is European hostility toward Japanese automakers. As much as the emergence of Japan as a major player on the automotive scene aroused horrendous racism and nationalistic furor in the U.S., that hasn’t significantly dissuaded Americans from buying Japanese cars, to the point that domestic automakers have more or less abandoned many segments of the market to the Japanese and Koreans. European markets have not been nearly so amenable, and even products Japanese automakers have designed specifically for Continental or British tastes have often been commercial duds. Applying that chauvinism to the early seventies, it’s also not hard to envision a scenario where Toyo Kogyo partnership in a Comotor-type JV ends up leading European punters and pundits deciding that rotary engines are too Japanese, which combined with the pressures of the OPEC embargo might also have been a death knell.

          1. Volkswagen could have attempted to use the rotary in more niche segments like Mazda did with front-engined sportscars though mid-engined in Volkswagen’s case, otherwise Volkswagen could be a passive beneficiary at best upon buying NSU.

          2. As it says in the Ro80 article, there was a lot of enthusiasm within Audi-NSU for the planned Ro80 successor, including some fairly serious talk of installing its 1.5-liter KKM 871/EA871 engine in the Audi C2. However, the minority shareholder settlement would have made using that or other Wankel engines in Volkswagen models fairly costly, which I think was a big part of why the whole plan ultimately didn’t go anywhere.

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