FISA imposed a ban on ground-effect aerodynamics during . By then, however, turbocharged engines, which Renault had pioneered in , were producing over and were essential to be competitive. By , a BMW turbocharged engine achieved a flash reading of pressure, estimated to be over in qualifying for the . The next year, power in race trim reached around , with boost pressure limited to only 4.0 bar. These cars were the most powerful open-wheel circuit racing cars ever. To reduce engine power output and thus speeds, the FIA limited fuel tank capacity in , and boost pressures in , before banning turbocharged engines completely in .