The muscle car era, lasting from 1965 to 1973, left a lasting impact on American automobile history, characterized by powerful V6 and V8 engines in medium-sized chassis. Popular models like the Pontiac GTO and Ford Mustang emerged during this time, but the rise in insurance costs and the gas crisis led to their decline in the mid-70s. Despite the end of production, muscle cars remain highly sought after, with their value expected to continue increasing.