The seeds of the BT50 were planted as early as mid-1979, when Niki Lauda's growing frustration with the uncompetitive Alfa-powered BT48 prompted discussions about alternative engine supply. While those particular talks did not lead anywhere, Brabham and BMW came to an engine agreement in the summer of 1980. Bernie Ecclestone, who owned Brabham, judged that turbo engines would define Formula One's competitive landscape in the near term, and the BMW M12/13 — a development of the company's existing four-cylinder iron block with a four-valve cylinder head from Formula Two — was selected as the route forward.
Initial testing of the BMW engine began in late 1980 using a modified BT49, while Murray worked on the purpose-built BT50. Completed in mid-1981, the BT50 carried over several elements from the BT49, including double wishbone suspension with semi-inboard pullrod coil spring and damper units, and an aluminium monocoque tub stiffened with carbon panels. A 180-litre fuel cell accommodated the turbo engine's greater fuel consumption. The car weighed 590 kilograms, ten more than its predecessor. The Hewland/Alfa gearbox inherited from 1976 initially struggled to handle the BMW engine's power and torque output. The BT50 was among the first Formula One cars to carry onboard telemetry for monitoring fuel injection.
The BT50 made its first public appearance at the 1981 British Grand Prix in practice, where Piquet set a time 0.7 seconds slower than his BT49 qualifying effort but recorded 309 km/h through the speed trap — 24 km/h faster than the normally aspirated car. Development testing was arduous; in one session at Paul Ricard alone, the team suffered nine engine failures.
Brabham entered the 1982 South African Grand Prix with three BT50s, Piquet qualifying second. Both cars retired early, Piquet spinning off on lap 4 and Patrese suffering a turbo bearing failure. Judging the engines unready, Ecclestone reverted to BT49s for the next two rounds. BMW, growing impatient, publicly threatened to terminate the relationship unless the BT50 was entered at the Belgian Grand Prix. Ecclestone complied, though qualifying was poor and Piquet finished a distant fifth.
A compromise arrangement followed: Piquet continued with the BT50 while Patrese raced the Cosworth-powered BT49 for several events. Patrese won the Monaco Grand Prix in his BT49, while Piquet struggled with the BT50 and failed to qualify in Detroit after consecutive engine failures during qualifying.
The turning point of Brabham's season arrived at Montreal. After an early misfire scare in practice, conditions improved markedly. Piquet qualified fourth and took the lead on lap 9, controlling the race on a day when cool temperatures favored the turbocharged engines. He won convincingly, recording BMW's first Formula One victory and ending a run of frustrating near-misses. Patrese, still in a BT49, completed a Brabham one-two.
From the British Grand Prix onward, Murray introduced a planned mid-race pit stop for refuelling, allowing both BT50s to start on lighter fuel loads, softer tyres, and higher boost levels. The strategy was sound in theory but repeatedly undermined by mechanical failures before the fuel stops could be completed. At the Austrian Grand Prix, Patrese led following Piquet's unscheduled early pitstop, came in for his own scheduled stop, and held the lead on rejoining — validating the concept — before retiring with engine failure three laps later. At the Swiss Grand Prix (held at Dijon-Prenois), both cars scored points: Patrese fifth after running nonstop, Piquet fourth. Those were the BT50's final race finishes; both cars retired at Monza and Las Vegas with clutch and engine problems respectively.
Piquet scored 20 points in the BT50, while Patrese contributed only 2 from his BT50 outings. Despite its unreliability, the car took one pole position and three fastest laps across the season, demonstrating the raw pace available from the BMW package. The shared experience between Brabham and BMW laid the groundwork for the BT52, with which Piquet won the 1983 Drivers' Championship.