The Muscle Grows

Other manufacturers showcased performance hardware in flashy limited-edition models. Chrysler led the way with its 1955 C-300, an inspired blend of Hemi power and luxury-car trappings that became the new star of NASCAR. With 300 horsepower (224 kW), it was advertised as "America's Most Powerful Car".

Capable of accelerating from 0 to 60 mph (97 km/h) in 9.8 seconds and reaching 130 miles per hour (209 km/h), the 1955 Chrysler 300 is also recognized as one of the best-handling cars of its era. Two years later, the Rambler Rebel was the fastest stock American sedan, according to Motor Trend.

The popularity and performance of muscle cars grew in the early 1960s, as Mopar (Dodge, Plymouth, and Chrysler) and Ford battled for supremacy in drag racing. The 1962 Dodge Dart 413 cu in (6.8 L) Max Wedge, for example, could run a 13-second 1/4-mile dragstrip at over 100 miles per hour (161 km/h). By 1964, General Motors' lineup boasted Oldsmobile, Chevrolet, and Pontiac muscle cars, and Buick fielded a muscle car entry a year later. For 1964 and 1965, Ford had its 427 cu in (7.0 L) Thunderbolts, and Mopar unveiled the 426 cu in (7.0 L) Hemi engine. The Pontiac GTO was an option package that included Pontiac's 389 cu in (6.4 L) V8 engine, floor-shifted transmission with Hurst shift linkage, and special trim. In 1966 the GTO became a model in its own right. The project, led by Pontiac division president John DeLorean, technically violated GM's policy, limiting its smaller cars to 330 cu in (5.4 L) displacement, but the new model proved more popular than expected, and inspired GM and its competitors to produce numerous imitators. The GTO itself was a response to the Dodge Polara 500 and the Plymouth Sport Fury, which in 1962 had been shrunk to intermediates.

American Motors, though late entering the muscle car market, produced "an impressive array of performance cars in a relatively short time," said Motor Trend. "The first stirrings of AMC performance came in 1965, when the dramatic, if ungainly, Rambler Marlin fastback was introduced to battle the Ford Mustang and Plymouth Barracuda." Although the Marlin was a flop in terms of sales and initial performance, AMC gained some muscle-car credibility in 1967, when it made both the Marlin and the "more pedestrian" Rebel available with its new 280 hp (209 kW; 284 PS), 343 cu in (5.6 L) "Typhoon" V8. In 1968, the company offered two pony car muscle car contenders: the Javelin and its truncated variant, the AMX.

Although the sales of true muscle cars were relatively modest by total Detroit production standards, they had value in publicity. Competition between manufacturers meant that buyers had the choice of ever-more powerful engines. A horsepower war was started that peaked in 1970, with some models advertising as much as 450 hp (336 kW; 456 PS).