Chevrolet was founded in 1911 and as early as 1918 had become a division of General Motors. However, this did not prevent Chevrolet cars becoming some of the most sought after vehicles in the world. If anything, the merger with GM spurred Chevrolet's growth and by 1923 production had reached the one million mark. The company also had an eye on promoting Chevrolet sales outside the United States and an assembly plant was built in Denmark. Chevrolet was also to the forefront in technical innovation; by the end of 1920s the company had produced its first 6-litre engine and was soon to introduce articulated braking. As Chevrolet sales continued to rocket, further technical innovations were introduced, including no draught ventilation, manifold heat control, vacuum spark control and independent front suspension. The 1950s and 60s saw the development of the muscle car and Chevrolet was very much to the forefront. The Chevy Bel Air was particularly popular with the American youth of the day, hooked on power, style and speed. Chevrolet were able to add muscle to their range with the introduction of their small block V8 engine in 1955. During the 1960s the company launched the Impala, the Corvette Stingray, the Chevy II and the Camaro. Even today, used Chevrolet Camaros or Corvettes remain a popular buy with enthusiasts. The oil crisis of the 1970s and higher insurance premiums proved to be the death knell of the muscle car. However, by the 1980s Chevrolet were back producing powerful cars such as the Camaro IROC-Z, which by 1987 was fitted with a 5.7-litre engine. The Monte Carlo SS Aerocoupe package was also available and selling well. The fact that Aerocoupes are still being raced on tracks around the world today demonstrates the strength of Chevrolet's technical innovation. The technology of Chevrolet cars has undoubtedly been the company's great success story.