Pity the second-generation Chevrolet Camaro. Born late — a delivery fraught with complications — it was nearly snuffed out in adolescence. Although it survived to a ripe old age, the second-gen Camaro has never inspired the same nostalgia as its beloved 1967-1969 predecessor, perhaps because it arrived in the fray of one of the most contentious public debates of the 20th century: the battle over automotive emissions and the use of lead as a gasoline additive. This is the story of the 1970-1981 Chevrolet Camaro and the rise and fall of leaded gasoline.
THE SECOND GENERATION CHEVROLET CAMARO
The first-generation Chevrolet Camaro, Chevrolet’s belated response to the Ford Mustang, bowed in the fall of 1966 as a 1967 model. Although it won respect for its performance and muscular appearance, neither the Camaro’s looks nor its muscle were enough to let it seriously challenge the popularity of the Mustang. Dearborn’s “pony car” regularly outsold the Camaro (and its F-body sister, the Pontiac Firebird) by a considerable margin. Before its first model year was over, however, Hank Haga’s Chevrolet Styling Studio 2 was already at work on the second-generation Camaro.
The new Camaro was planned for the 1970 model year, which would ordinarily have put it on sale in the fall of 1969. As it happened, the new car didn’t appear until February 26, 1970, around five months late. There is a popular assumption that the delay was caused by labor issues — GM clashed repeatedly with the United Auto Workers union (UAW) between 1969 and 1972 and there were several lengthy strikes during this period. However, the Camaro Research Group says the real reason for the delay was a serious problem with the new car’s complex rear quarter panel dies, which forced Fisher Body first to modify and then to completely redesign the affected tooling. That in turn forced GM to keep the 1969 Camaro in production for an extra four months.
When the second-generation Chevrolet Camaro finally did appear, it made a tremendous splash. It was one of the most radical-looking new designs the industry had seen since the excesses of 1959.
Unlike the Mustang, whose successive revamps from 1964 to 1973 represented a steady evolution of the original concept, the new Camaro was an almost complete stylistic break with its predecessor. The first Camaro, as we have previously seen, evolved from the “Super Nova” concept car of the early sixties and essentially married the stylistic philosophy of the second-generation Chevrolet Corvair (1965-1969) with the short-deck, long-hood proportions popularized by the Mustang; park a 1967 Chevrolet Camaro next to a post-1965 Corvair and the family resemblance of their basic body shapes is readily apparent. In contrast, new Camaro looked more like something from Italy than Detroit. It featured a curvaceous nose and gaping grille that recalled early-sixties Ferrari or Maserati GT cars — particularly on Rally Sport models, which had no bumper ahead of their grille openings.
Under the skin, the new F-body was much more familiar. It was about 2 inches (51 mm) longer, slightly wider, and somewhat lower than the 1969 Camaro, but was structurally very similar. It retained the first-generation car’s semi-monocoque construction, with a separate front subframe carrying the engine and front suspension, and suspension design and powertrain choices were substantially the same as before. Front disc brakes were newly standard, but the four-wheel discs that had been available on a very limited basis in 1969 were gone. The new Camaro was almost 200 pounds (90 kg) heavier than the old, thanks to the addition of new side-guard door beams as well as the more complex inner body stampings necessary to accommodate its curvy shape.
The high-performance Z/28 option package returned for 1970, but Chevrolet abandoned the earlier Z/28’s high-strung 302 cu. in. (4,942 cc) engine in favor of the new 350 cu. in. (5,733 cc) LT-1. The LT-1, shared with the Corvette, was rated at 360 gross horsepower (268 kW) — about as a strong as the underrated 302, but far more tractable. An additional advantage was that the Z/28 could now be ordered with automatic transmission, whereas first-gen Z/28s had required a four-speed manual. A big-block V-8 remained optional on other Camaros. Chevrolet still called the big Turbojet V-8 a “396,” but it was now actually 402 cubic inches (6,587 cc), rated at 350 gross horsepower (261 kW). Chevrolet briefly announced that the Camaro would offer the big 454 cu. in. (7,443 cc) LS-6 engine offered in the 1970 Chevelle SS, rated at a whopping 450 gross horsepower (336 kW), but the option was dropped before it went into production.
The 1970 Chevrolet Camaro was just about as fast as its predecessor despite its extra weight. Car and Driver put its well-prepared automatic Z/28 across the quarter-mile line (402 meters) in the low 14-second range with a trap speed of slightly over 100 mph (161 km/h); Motorcade‘s Dave Epperson managed similar figures. That was excellent performance, but the bottom was about to fall out.
GETTING THE LEAD OUT
About nine months after the Camaro’s belated debut, the U.S. Congress unanimously passed the Clean Air Act of 1970, empowering the recently created Environmental Protection Agency (EPA) to set and enforce standards for air pollution. The federal government had begun setting limits on automotive emissions for the 1968 model year, two years after the state of California initiated its own, more-stringent standards, but the Clean Air Act called for a 90% reduction in automotive emissions by 1975. It also reopened a very old can of worms: the use of lead in gasoline.
To understand the history of leaded gasoline, we must examine some of the basic engineering concepts involved. A four-stroke engine, like that used in most automobiles, compresses its air-fuel mixture before burning it. One of the most effective ways to improve both an engine’s specific output (its power per unit of displacement) and its specific fuel consumption (fuel burned per unit of power produced) is to increase the static compression ratio (the ratio of the swept volume of each cylinder and combustion chamber when the piston is at bottom dead center — its lowest point — to the combustion chamber volume when the piston is at top dead center — its highest point).
This has two effects: First, it increases the density of the mixture, packing oxygen and fuel molecules more tightly together, which allows more complete combustion. Second, it increases the energy of that mixture through adiabatic heating, allowing more energy to be extracted from the mixture when it burns. As a result, a higher compression ratio improves both power and fuel economy, which is why the auto industry — spearheaded by General Motors — has long been enthusiastic about high-compression engines like the Camaro’s high-revving LT-1.
A major drawback of raising a gasoline engine’s compression ratio is that increasing the temperature of the mixture by compressing it increases the chances that the mixture will ignite either before or after the spark plugs fire. This is called autoignition, also known as detonation, pinking, or engine knock. Because knock is uncontrolled detonation, typically occurring around hot spots in the combustion chamber, it has the potential to cause severe engine damage. Finding ways to raise the compression ratio of gasoline engines without causing catastrophic knock was a daunting challenge for early automakers and engine manufacturers.
PUTTING THE LEAD IN LEADFOOT
One of the engineers pursuing that goal was Charles F. Kettering, the founder of Delco (later a GM division) and, after selling Delco in 1916, the Dayton Metal Products Corporation (DMPC). Kettering was a brilliant and prolific engineer involved in many major automotive innovations, notably the development of the first electric starter motor, adopted by Cadillac in 1912.
Not long after that, Kettering became interested in finding ways to control engine knock to allow higher compression ratios. It was already understood that the use of different fuels affected a given engine’s susceptibility to knock. Ethyl alcohol, for example, was already known to provide greater knock resistance than gasoline, although the reasons were not yet well understood. Kettering and his assistant, engineer Thomas Midgley, Jr., who had worked with Kettering at Delco and joined him at DMPC, hypothesized (correctly) that the knock resistance of a given fuel depended on the fuel’s ability to absorb heat without igniting. From that, they concluded that it would be possible to increase a fuel’s resistance to detonation by altering its formulation or using additives.
In 1917, Kettering and Midgeley developed an antiknock fuel using a mixture of cyclohexane and benzene, which they successfully demonstrated to the U.S. Army Air Corps. In 1918, DMPC filed a patent on this use of benzene, intending to manufacture it, but the end of the war and the withdrawal of Army interest put the project on the shelf.
A year later, Kettering sold DMPC to General Motors and became head of GM’s research subsidiary, again bringing Midgeley with him. GM was very interested in the idea of antiknock fuel additives, which had obvious commercial potential — particularly considering that more than a third of GM stock was then owned by the oil company E. I. du Pont de Nemours and GM and du Pont shared several board members.
Interestingly, the initial impetus for increasing the compression ratios of automotive engines was not the quest for more power, but rather the need for greater fuel economy. While we tend to think of oil shortages as a modern preoccupation, there was considerable anxiety even before 1920 that U.S. oil consumption would soon outpace domestic reserves, eventually forcing the U.S. to buy much of its oil overseas. Kettering believed that wider use of more efficient engines would help to forestall that eventuality until alternatives to fossil fuels became available.
At the time, Kettering believed that oil’s principal successor would probably be ethanol. Midgeley demonstrated that a 70/30 blend of gasoline and ethanol provided excellent knock resistance, allowing what were for the time exceptionally high compression ratios. However, Kettering recognized that producing ethanol in large quantities for fuel use would require the development of means to produce alcohol from cellulose farm waste rather than food crops — something that was becoming feasible, but not yet economically viable. In the interim, Kettering and Midgeley sought a “low percentage” antiknock additive for gasoline, a goal that dovetailed with their employer’s commercial ambitions.
In late 1921, after years of extensive trial and error that by some accounts involved thousands of experiments, Midgeley finally hit upon an effective answer: lead tetraethide, more commonly called tetraethyl lead (TEL). Although TEL was not easy to produce and making it a workable fuel additive took further development, even small quantities could significantly increase gasoline’s heat absorption capacity, which greatly improved knock resistance.
General Motors first demonstrated the use of TEL as an antiknock additive in the summer of 1922. By late 1923, du Pont had developed several patented means of manufacturing TEL, which allowed commercial sales to commence. In mid-1924, GM and Standard Oil of New Jersey (the predecessor of the modern Exxon-Mobil Corporation) formed the jointly owned Ethyl Corporation to sell TEL under the trade name “Ethyl.” The name was suggested by Kettering, who became the new company’s first president.
Despite early public controversy about the use of TEL, Ethyl was very successful. By the late thirties, it was in nine out of every 10 gallons of gasoline sold in the U.S. and was beginning to proliferate overseas. High-octane leaded aviation gasoline fueled many of the military aircraft engines of World War II. By the fifties, there was also high-octane premium pump gasoline, supporting the emergence of a new generation of powerful OHV V-8s.
(As a side note, in 1926, Ethyl scientists developed the octane scale (based in part on an idea of Midgley’s) for quantifying the knock resistance of a given fuel. The scale was based on the properties of two of the hydrocarbons commonly contained in gasoline: heptane (n-Heptane) and iso-octane (2,2,4-Trimethylpentane). Since heptane’s knock resistance was poor, it became the zero point of the scale while pure iso-octane was assigned a value of 100. A fuel’s octane number was its knock resistance relative to a blend of heptane and iso-octane; for example, a fuel with knock resistance equivalent to a 50/50 blend of the two hydrocarbons would have an octane number of 50 while a fuel comparable to a 95/5 blend of iso-octane and heptane would have an octane number of 95. Some fuels, such as pure ethanol, actually have octane numbers lower than pure heptane or higher than pure iso-octane, providing octane numbers less than 0 or more than 100. There are now several different octane rating systems using different methods to calculate a given fuel’s knock resistance.)
THE LEADED GASOLINE CONTROVERSY
Aside from the manufacturing and engineering challenges it presented, the principal drawback of TEL as a fuel additive was that lead is a potent and deadly neurotoxin. The dangers of lead poisoning have been known for hundreds of years, although before World War II, lead was still widely used in a variety of consumer products like paint and glassware.
Public health advocates like Yandell Henderson of Yale University and Alice Hamilton of Harvard Medical School, who had written about the dangers of lead poisoning for more than 15 years, were unhappy about the use of TEL in motor fuel almost from the start. Their concern was not theoretical: Some members of Kettering’s own staff, including Midgley, suffered the effects of lead exposure and more than a dozen du Pont and Standard Oil workers died of lead poisoning between 1923 and 1925. The state of New Jersey actually filed criminal charges against Standard Oil in connection with the deaths of workers at a plant there, but a grand jury did not bring an indictment.
Ethyl temporarily suspended production in 1925. The U.S. Public Health Service held public hearings on TEL, at which representatives of GM, Standard Oil, and Ethyl claimed there were no viable alternatives to TEL and dismissed the public outcry as unwarranted alarmism. The surgeon general appointed an investigatory committee, whose report, issued in January 1926, concluded that there were insufficient grounds to ban the use of TEL in gasoline, although the committee acknowledged that the data was very limited and strongly recommended further research. The PHS didn’t follow up on that recommendation, but in 1927, the surgeon general specified a voluntary limit of 3 cc of lead per gallon (raised in the late fifties to 4 cc per gallon, equivalent to about 4.23 grams per gallon or 1.12 grams per liter).
The controversy soon faded from the public consciousness in the U.S., although similar questions were raised when TEL was adopted in the U.K. By the mid-thirties, the safety of Ethyl was taken sufficiently for granted that in 1936, the Federal Trade Commission ordered an Ethyl competitor, Cushing Gasoline and Refinining Company, to desist from charactering Ethyl’s product as dangerous or unhealthy.
After the war, an emerging body of scientific research linked high blood lead levels due to environmental lead contamination (including the burning of leaded gasoline) to a sobering array of health problems, particularly among children. (Today, the Centers for Disease Control consider blood lead levels of more than 5 micrograms per deciliter grounds for public health action.) Some of the binding chemicals used with TEL, such as ethylene dibromide (EDB), were later identified as health hazards as well; the EPA now warns that exposure to EDB (usually through the consumption of contaminated water) can contribute to liver, stomach, and kidney problems and an elevated risk of cancer. Nonetheless, the oil and auto industries continued to deny that the use of leaded gasoline posed any substantive public health risks.
In the sixties, leaded gasoline became one of the targets of an emerging U.S. movement to improve automotive safety and reduce harmful emissions. In 1969, U.S. Secretary of Health, Education, and Welfare Robert Finch proposed that major oil companies begin phasing out leaded gasoline starting in mid-1971.
THE MOVE TO UNLEADED GASOLINE
Surprisingly, the first U.S. automaker to support the push for lead-free gasoline was General Motors, whose president, Ed Cole, announced in January 1970 that GM could reduce the compression ratios of all its engines to make them compatible with unleaded gasoline starting with the 1971 model year. General Motors and Standard Oil had divested themselves of the Ethyl Corporation in 1962, but Cole’s announcement nonetheless startled many in the auto industry.
Around the same time, Henry Ford II, chairman of Ford Motor Company, sent a letter to 19 major petroleum producers asking them to begin offering lead-free fuels. Leaded gasoline, whose use had been taken almost completely for granted even five years earlier, was suddenly on its way out.
Although some U.S. health officials now characterized lead as a public menace, the auto industry was careful to attribute the transition to unleaded gasoline not to any inherent health risk of leaded fuels, but to the need to prepare for the adoption of catalytic converters for emissions control. Leaded gasoline is incompatible with catalytic converters because lead deposits quickly foul the catalyst; lead has a similar effect on oxygen sensors, later adopted for electronic engine management systems.
In late 1973, the EPA announced the beginning of a mandatory phaseout of leaded gasoline. A lawsuit by du Pont and the Ethyl Corporation temporarily blocked that mandate, but in 1976, a federal court of appeals upheld the phaseout regulation; the U.S. Supreme Court declined to hear the case.
Editorials in the automotive press mostly condemned the transition to low-lead and lead-free gasoline. Many of the editors were already deeply critical of safety and emissions regulations, seeing them not as public health actions, but as overweening ‘nannyism’ by politicians and car-hating zealots with no engineering knowledge. The lowering of compression ratios to allow more emissions-control devices was seen as just another blow to the editors’ beloved sports cars and Supercars. (Ironically, the widespread adoption of catalytic converters and electronic engine controls — which, at least in the U.S. and Japan, were adopted primarily for emissions reasons — would later allow a performance renaissance, but that didn’t happen for more than a decade and would have seemed entirely improbable in the early seventies.)
THE FALL AND RISE OF THE CAMARO
General Motors kept its promise of lower compression ratios: For the 1971 model year, even the high-winding Chevrolet LT-1’s compression ratio dropped from 11.0:1 to 9.0:1.
In the Camaro, the effects were immediately apparent. Comparing their 1971 Camaro Z/28 to the 1970 model, Car and Driver found that the low-compression engine reduced quarter-mile trap speeds — a reliable measure of a car’s power-to-weight ratio — by almost 7 mph (11 km/h) even though the 1971 test car was almost 100 pounds (45 kg) lighter than the 1970 car. Although Chevrolet claimed that the reduced compression ratio cost the LT-1 engine only about 15 net horsepower (11 kW), the magazine’s editors estimated that the drop was more than 40 hp (30 kW).
The decline for 1971 was only the beginning. For 1972, the LT-1’s net horsepower fell to 255 hp (190 kW). The best quarter-mile time Road & Track‘s 1972 Z/28 automatic could manage was the mid-15-second range, with trap speeds of about 90 mph (145 km/h). For 1973, the LT-1 was replaced by the L-82, which had a milder camshaft with hydraulic rather than mechanical lifters. Rated at 245 net horsepower (183 kW), the L-82 was now the Camaro’s most powerful engine — the 402 had been dropped after the previous season. The milder engine had to move a heavier car; new 5 mph (8 km/h) bumper standards further inflated the F-body’s already substantial curb weight.
The Camaro’s ever-increasing weight and worsening power deficit were moot points for many buyers, who were now hit with prohibitive insurance surcharges on all but the mildest pony cars. Sales of all sporty cars were shrinking and the second-generation Camaro’s sales were further impacted by a lengthy work stoppage at the Camaro plant in Norwood, Ohio, that cut total production for the 1972 model year by around 40,000 units. More than 1,000 completed cars then had to be scrapped because they were finished too late to be legally sold as 1972 models; they didn’t meet the tougher federal safety and emissions standards that took effect for the 1973 model year.
Facing those problems, GM seriously considered dropping both the Camaro and its F-body sibling, the Pontiac Firebird. Other automakers were also cutting their losses; the Dodge Challenger, Plymouth Barracuda, and AMC Javelin would all expire in 1974 while Ford reinvented the Mustang as the Pinto-based Mustang II.
Thanks in part to a grassroots campaign both inside and outside GM, Chevrolet and Pontiac finally decided to stay the course. For 1974, the Camaro and Firebird received a facelift that neatly incorporated the new 5 mph bumpers. The revised styling inevitably lacked the purity of the earlier second-gen cars, but met the new federal requirements while preserving the F-bodies’ sporty image.
Although performance continued to erode due to greater weight and more stringent emissions standards, Camaro sales picked up nicely, no doubt helped by the greatly diminished competition. Both the Camaro and the Firebird remained popular and profitable enough to last through the 1981 model year.
The demise of leaded gasoline proved to be a protracted struggle. The Reagan administration attempt to roll back the lead phaseout in 1981, but political pressure forced them to relent the following year. Most U.S. automotive gasoline was lead-free by 1986, although the use of leaded fuel for on-road vehicles was not completely banned until the end of 1995. NASCAR didn’t adopt unleaded racing fuel until early 2007.
Ethyl and its rivals continued to aggressively market TEL outside the U.S. through the nineties. Japan had phased out leaded fuel in the mid-seventies, again prompted mostly by the planned adoption of catalytic converters, but unleaded fuel did not become widely available in Europe and the U.K. until the late eighties and the European Union didn’t ban leaded gasoline for passenger car use until 2000. Leaded petrol remained common in other nations, such as India, into the new century, but its use has rapidly declined over the past decade. In 2011, the UNEP Partnership for Clean Fuels and Vehicles estimated that only about a half a dozen countries still use leaded gasoline for motor vehicles. However, TEL is still used in aviation gasoline, although most modern avgas is 100-octane “low lead” rather than the earlier 130-octane “highly leaded” variety.
The transition to unleaded gasoline has been costly and some non-TEL octane boosters may be hazardous in their own right; while the EPA Office of Water says there’s not enough data to determine whether exposure to low levels of MTBE (methyl tertiary butyl ether) is a health hazard, the agency warns that higher levels of the additive may be carcinogenic. The good news is that the EPA estimates that Americans’ average blood lead levels dropped 78% between 1978 and 1986; a 2007 Amherst College study linked reduced blood lead levels to concurrent decreases in the incidence of violent crime. Still, lead doesn’t break down or decay, so the impact of past use of leaded gasoline may never entirely disappear.
What about the poor, beleaguered second-generation Camaro? Ironically, its popularity at the time has done no favors for its reputation today. Although the Camaro was never very common outside the U.S., if you’re an American of a certain age, the chances are that you either owned one or knew someone who did. Sheer ubiquity soon dulled the impact of styling that seemed so fresh and daring in the spring of 1970. By the time its replacement bowed in the fall of 1981, many people were more than ready to forget it and the era of stylistic excess, inflation, gas rationing, and controversy in which it appeared.
The early (1970-1972) second-gen cars have a strong fan base, but they’ve never been as desirable as the first-generation Camaro and probably never will be. That’s a shame — had the Camaro appeared before the smog and safety controversies, it would probably be considered a classic like its predecessor.
Sometimes, history has no mercy for those born in the wrong place at the wrong time.
NOTES ON SOURCES
Our sources for the history of leaded gasoline included Marshall Brain, “What does octane mean?” HowStuffWorks.com, 1 April 2000, auto.howstuffworks. com/ fuel-efficiency/fuel-consumption/ question90.htm, accessed 30 May 2008, Centers for Disease Control and Prevention, “Lead,” 15 June 2013, www.cdc. gov/ nceh/ lead/, accessed 7 April 2015; Environmental Protection Agency, “EPA Requires Phase-Out of Lead in All Grades of Gasoline” [press release], 28 November 1973, reprinted at www2.epa. gov/aboutepa/ epa-requires-phase-out- lead-all-grades-gasoline; “Methyl Tertiary Butyl Ether (MTBE): Drinking Water,” 15 November 2014, www.epa. gov/ mtbe/ water.htm, accessed 7 April 2015; and “Water: Basic Information about Ethlene dibromide in Drinking Water,” 9 February 2014, water.epa. gov/drink/ contaminants/ basicinformation/ ethylene-dibromide.cfm, accessed 15 April 2015; John Ethridge, “Gettin’ the Lead Out,” Motor Trend Vol. 22, No. 5 (May 1970), pp. 48-50; Maurice Hendry, “Hillbilly Genius: ‘The Great Boss Ket,'” Special Interest Autos #51 (June 1979), pp. 20-27; Jamie Kitman, “The Secret History of Lead,” The Nation March 2000; Jack Lewis, “Lead Poisoning: A Historical Perspective,” EPA Journal May 1985, reprinted at www2.epa. gov/ aboutepa /lead-poisoning-historical-perspective; UNEP Partnership for Clean Fuels and Vehicles, “Clearing House Presentation,” 26 October 2011, www.unep. org, accessed 7 April 2015; Hajime Nishimura, ed., How to Conquer Air Pollution: A Japanese Experience (Studies in Environmental Science 38) (Amsterdam, Netherlands: Elsevier Science Publishers B.V., 1989); Jessica Wolpaw Reyes, “Environmental Policy as Social Policy? The Impact of Childhood Lead Exposure on Crime,” National Bureau of Economic Research (NBER) Working Paper No. 13097, www.nber. org/papers/w13097, issued May 2007, accessed 1 June 2008; William K. Toboldt and Larry Johnson, Goodheart-Willcox Automotive Encyclopedia (South Holland, IL: The Goodheart-Willcox Company, Inc., 1975); the Wikipedia® entry for “Octane rating” (en.wikipedia.org/wiki/Octane_rating, accessed 30 May 2008); Tim Wusz, “Octane Number Confusion,” Runyard.org, 16 November 1995, www.runyard. org/jr/CFR/OctaneExplanation.htm, accessed 30 May 2008; and the following papers by William Kovarik, Ph.D., reprinted on his website: “Charles F. Kettering and the 1921 Discovery of Tetraethyl Lead In the Context of Technological Alternatives,” originally presented to the Society of American Engineers Fuels & Lubricants Conference, Baltimore, MD, 1994, revised 1999, www.radford. edu/~wkovarik/papers/kettering.html, accessed 30 May 2008; “Ethyl: The 1920s Environmental Conflict Over Leaded Gasoline and Alternative Fuels,” 26 March 2003, www.radford. edu/~wkovarik/papers/ethylconflict.html, accessed 30 May 2008; “Henry Ford, Charles Kettering, and the ‘Fuel of the Future,'” Automotive History Review #32 (Spring 1998), pp. 7-27, www.radford. edu/~wkovarik/papers/fuel.html, accessed 30 May 2008; and “Leaded gasoline: history and current situation,” n.d., www.radford. edu/~wkovarik/ethylwar/, accessed 30 May 2008.
We also consulted the following patents: Fred E. Aseltine, assignor to General Motors Research Corporation, “Method and Means for Incorporating an Antiknock Substance with a Motor-Fuel Mixture,” U.S. Patent No. 1,467,222 A, filed 17 December 1920, published 4 September 1923; William S. Calcott, assignor to E.I. Du Pont de Nemours & Company, “Process of Making Tetra-Alkyl Lead,” U.S. Patent No. 1,559,405 A, filed 5 October 1922, published 27 October 1925; Carl O. Johns, assignor to Standard Oil Development Company, “Motor Fuel,” U.S. Patent No. 1,757,837, filed 21 May 1924, published 6 May 1930; Charles F. Kettering and Thomas Midgley, Jr., assignors to General Motors Corporation, “Motor Fuel,” U.S. Patent No. 1,605,663 A, filed 15 April 1922, published 2 November 1926; Thomas Midley Thomas Midgley Jr., assignor to General Motors Corporation, “Process of Making Organic Lead Compounds,” U.S. Patent No. 1,622,228, filed 19 May 1923, published 22 March 1927; Thomas Midgley, Jr., assignor to the Dayton Metal Products Company, “Fuel for Internal-Combustion Engines,” U.S. Patent No. 1,296,832, filed 7 January 1918, published 11 March 1919; Thomas Midgley, Jr., assignor to General Motors Research Corporation, “Aniline Injector,” U.S. Patent No. 1,501,568 A, file 15 October 1920, published 15 July 1924; and “Motor Fuel,” U.S. Patent No. 1,491,998, filed 4 October 1918, published 29 April 1924; Kenneth P. Monroe, assignor to E.I. Du Pont de Nemours & Company, “Production of a Tetra-Alkyl Lead,” U.S. Patent No. 1,645,389, filed 23 October 1922, published 11 October 1927; and Robert E. Wilson, “Antiknock Compounds,” U.S. Patent No. 1,815,753 A, filed 8 November 1924, published 21 July 1931.
Sources on the 1970½-1981 Chevrolet Camaro included the Camaro Research Group website, “Primary Research and Restoration Data for First-Generation Camaros,” ed. Rich Fields, 1998-2008, www.camaros. org, accessed 30 May 2008; C. Edson Armi, The Art of American Car Design: The Profession and Personalities (University Park, PA: The Pennsylvania State University Press, 1988); the Auto Editors of Consumer Guide, Encyclopedia of American Cars: Over 65 Years of Automotive History (Lincolnwood, IL: Publications International, 1996); John Gunnell, ed., Standard Catalog of American Cars 1946-1975, Revised 4th Edition (Iola, WI: Krause Publications, 2002); Dave Holls and Michael Lamm, A Century of Automotive Style: 100 Years of American Car Design (Stockton, CA: Lamm-Morada Publishing Co. Inc., 1997); Michael Lamm, “The Fabulous Firebird: Developing the Second Generation” (which is actually an excerpt from Lamm’s book, The Fabulous Firebird), Special Interest Autos #57 (June 1980), pp. 42-49; Mike Maciolak, Camaro Model Info, 2006, www.nastyz28. com, accessed 30 May 2008; and the following vintage road tests: Ron Wakefield, “1970 Camaro & Firebird: Chevrolet & Pontiac versions of a new American GT, plus a facelifted Corvette for 1970,” Road & Track March 1970, reprinted in Firebird and Trans-Am Muscle Portfolio 1967-1972, ed. R.M. Clarke (Cobham, England: Brooklands Books Ltd., ca. 1998); “Chevrolet Camaro: The Z/28 version would be every bit as much at home on the narrow, twisting streets of Monte Carlo as it is on Interstate 80,” Car and Driver May 1970; “1970 Chevrolet Camaro,” Road & Track May 1970; Dave Epperson, “Zapped by a Z28 Camaro,” Motorcade May 1970; “New and Improved: The Camaro SS approaches GT status,” Road Test August 1970; “Chevrolet Camaro Z28: Underneath last year’s smooth exterior beats 1971’s low-compression engine,” Car and Driver May 1971; and “Camaros for Everything: An engineered guide through a thicket of options for luxury, performance or combinations thereof,” Road & Track April 1972, all of which are reprinted in Camaro Muscle Portfolio 1967-1973, ed. R.M. Clarke (Cobham, England: Brooklands Books Ltd., ca. 1992).