continued in the series, the works team withdrew to concentrate on Formula One (and USAC, for several years). Team McLaren went on to become a several time F1 champion and is still a part of that series. Porsche The Porsche 908 spyder was used in Can-Am, but was underpowered (350 hp) and mainly used by underfunded teams. It did win the 1970 Road Atlanta race, when the more powerful cars fell out. The 917PA, a spyder version of the 917K Le Mans car, was raced, but its normally aspirated flat-12 was underpowered (530 hp). In 1971 the 917/10 was introduced. This was not turbocharged, but was lighter and had cleaner body work, and Jo Siffert managed to finish fourth in the championship. For 1972 the 917/10K with a turbocharged 900 horsepower five-litre flat-12 was introduced. Prepared by Roger Penske and driven by Mark Donohue and George Follmer these cars won six of the nine races. In 1972 Porsche introduced an even more powerful car, the 917/30KL. Nicknamed the "Turbopanzer" this car was seen as a monster. With 1,100 or 1,580 horsepower (820/1161 kW in race or qualifying trim) available from its 5.4 litre flat-12 and weighing 1,800 lb (816 kg) with better downforce this car won six of eight races in the 1973 championship. Porsche's dominance was such that engine rules were changed to try to reduce the lack of competition for one marque by enforcing a fuel-consumption rule for 1974. This kind of alteration of rules to promote equality is not unknown in other forms of American motorsport. The category that the car had been created for and competed in was discontinued and in 1975 Donohue drove this car to a closed-course world-speed record of 221 mph (average)(356 km/h) at the Talladega Superspeedway (then called the "Alabama International Motor Speedway"). It was capable of 240 mph (386 km/h) on the straights. Chaparral Jim Hall's Chaparrals were very innovative, following his success in the United States Road Racing Championship (USRRC). The 2 series Chaparrals (built and engineered with a high degree of covert support from Chevrolet's research and development division) were leaders in the application of aerodynamics to race cars culminating with the introduction of the 2E in 1966, the first of the high wing race cars. The 2E was a defining design, and the 2G was a development of that basic design. The FIA banned movable aerodynamic devices and