Brabham was the world's largest manufacturer of customer open wheel racing cars in the 1960s, and had built more than 500 cars by 1970. During this period, teams using Brabham cars won championships in Formula Two and Formula Three and competed in the Indianapolis 500. In the 1970s and 1980s, Brabham introduced innovations such as the controversial but successful 'fan car', in-race refuelling, carbon brakes, and hydropneumatic suspension. The team won two more Formula One drivers' championships in the 1980s with Brazilian Nelson Piquet, and became the first to win a drivers' championship with a turbocharged car.