A nearly dead breed of predominately American cars that have the primary focus of being relatively inexpensive considering their high performance. This is achieved by ignoring most comfort oriented features seen in similarly priced cars.
They were most popular in their golden age - the 50s through the early 70s - up until the energy crisis. During that time, advances in suspension, brakes, tires, and frame consistency/rigidity had not yet been made, making the cars notorious for their rough ride, poor handling, and ineffective brakes which were made more dangerous by their high acceleration and top speed. For this reason, muscle cars have the stereotype of only being effective at straight line performance, but the few remaining muscle cars have proven otherwise.
The boom of the 90s saw a bit of resurgence with American muscle cars and even some foreign competitors, but their impracticality has kept them from being at the forefront of the public eye's desire or automakers' concerns.
The 1968 GTX Roadrunner with a 426 cubic inch engine had 425hp and 490lb-ft, was capable of a quarter mile in 13.4 seconds - a feat rarely obtained by today's cars. It had upgraded handling and other essentials, but had a spartan interior, even lacking carpets.
The 2002 Camaro SS had handling that rivaled and acceleration that beat nearly every car costing under $60,000. It even got 28mpg on the highway thanks to its high torque and six speed transmission. But it was 2-doors only, had mediocre leg room in both front and back, and sub par creature comforts considering that it cost over $30,000.
Modern day examples of foreign attempts at the single-minded goal of a car with high performance above all else (muscle cars) are include the: Subaru WRX STi, Mitsubishi Lancer Evolution, Nissan 350z, Honda S2000, and Toyota Supra.