In the 1960s, Brabham was the world's largest manufacturer of open-wheel racing cars for sale to customer teams; by 1970 it had built more than 500 cars. During this period, teams using Brabham cars won championships in Formula Two and Formula Three. Brabham cars also competed in the Indianapolis 500 and in Formula 5000 racing. In the 1970s and 1980s, Brabham introduced such innovations as in-race refuelling, carbon brakes, and hydropneumatic suspension. Its unique Gordon Murray-designed "fan car" won its only race before being withdrawn.