GM has long worked on alternative-technology vehicles, and has led the industry with ethanol-burning flexible-fuel vehicles that can run on either E85 (ethanol) or gasoline. The company was the first to use turbochargers and was an early proponent of V6 engines in the 1960s, but quickly lost interest as muscle car popularity increased. They demonstrated gas turbine vehicles powered by kerosene, an area of interest throughout the industry, but abandoned the alternative engine configuration in view of the 1973 oil crisis. In the 1970s and 1980s, GM pushed the benefits of diesel engines and cylinder deactivation technologies with disastrous results due to poor durability in the Oldsmobile diesels and drivability issues in the Cadillac V8-6-4 variable-cylinder engines. In 1987, GM, in conjunction with AeroVironment, built the Sunraycer, which won the inaugural World Solar Challenge and was a showcase of advanced technology. Much of the technology from Sunraycer found its way into the Impact prototype electric vehicle (also built by Aerovironment) and was the predecessor to the General Motors EV1.