Regardless how it is credited, the horsepower race centered around the V8 engine and the muscle-car era lasted until new smog regulations forced dramatic changes in OEM engine design in the early 1970s. This in turn opened up new opportunities for aftermarket manufacturers like Edelbrock. Each year brought larger engines and/or increases in horsepower, providing a catalyst for customers to upgrade to newer models. Automobile executives also deliberately updated the body designs yearly, in the name of "planned obsolescence" and added newly developed or improved features such as automatic transmissions, power steering, power brakes and cruise control, in an effort to make the previous models seem outdated and facilitate the long drive from the suburbs. Record sales made the decade arguably the "golden era" of automobile manufacturing.
