Testing of the M12/13 got underway in late 1980 with a Brabham BT49 chassis converted to accept the engine. The team's designer, Gordon Murray, designed a new car, the BT50 for the engine, but it was not completed until well into the season. The BT50 featured a longer wheelbase and a larger fuel cell than the BT49 to accommodate the requirements of the more powerful turbo engine, and was also one of the first Formula One cars to feature onboard telemetry as a means of monitoring the engine's fuel injection. The team's lead driver, Nelson Piquet, tested the BT50 throughout 1981, but the car proved chronically unreliable until Bosch introduced a digital electronic management system at the end of the year, which immediately improved the situation. The BT50 made a solitary race weekend appearance at the 1981 British Grand Prix, where Piquet set a qualifying time 0.7 seconds slower than his effort in the Cosworth DFV-powered BT49. The BT50 handled poorly but recorded through the speed trap, some faster than the BT49. Meanwhile, Brabham won the Drivers' Championship with Piquet, who drove the BT49 throughout the season.