What exactly happened to muscle cars in the 1970s? When you’re reading about the history of the American muscle car, there’s a very obvious demarcation. You have the raging hellbeasts that lumbered and roared their way down highways across the nation in the 1950s, 60s, and early 70s. Then, suddenly, they just die off. Their extinction was as sudden as the dinosaurs’, but why? There’s quite a few factors that caused this lull in production, and in this article, we’re going to explore them all.

The first rumblings that something big was about to happen in the auto industry began in 1965. It was during this year that Ralph Nader, long before he attempted to run for the presidency, published Unsafe at Any Speed. This book was a groundbreaking study of the lax attitude towards safety measures taken by many vehicle manufacturers. The Chevrolet Corvair drew large amounts of fire in the study. Its lack of a anti-roll bar meant that tires had to be over pressurized, which led to a dangerous amount of oversteer. Other criticisms from Nader included ornate ornamentation that reflected sunlight into drivers’ eyes, non-standardized gear shift layouts that could lead to the driver shifting into reverse by mistake, door strength, pedestrians’ safety not being taken into account by cars’ exteriors, and air pollution. It would be the latter that eventually killed off muscle cars.

The auto industry, as you might imagine, did not respond well to this exposé. GM carried out a campaign of harassment and intimidation against Nader, for which they later apologized, and were forced to pay Nader $425,000. In response to the study, the federal government created the Department of Transportation.

Flash forward five years, and you come to the Clean Air Act. Though this act had been passed in 1963, sweeping amendments were made in 1970. These included, most notably for the contents of this article, new emissions regulations for both factories and automobiles. Prior to these regulations, muscle cars tended to feature high-compression engines that required both high-octane fuel and lead, as a valve lubricant. However, thanks to the new laws, the compression ratio had to be cut, and the cars required regular-grade fuel. Couple these with new safety standards requiring heavier bumpers and you end up with lower performance. Companies had also switched the numbers on their advertising from gross to net horsepower, which made the loss of power look even worse than it was. Consumers were now being offered cars that had around 100 horsepower less than the older models.