The BT49D represented the fourth major update to a chassis that had first raced in 1979. It used lighter composite materials throughout and one-piece bodywork compared to the earlier BT49C. By the 1982 season, the cars had to be ballasted to reach the minimum weight limit of 580 kilograms specified in the regulations, a marker of how efficiently Murray had reduced the car's mass over successive variants.
The 60 mm minimum ground clearance rule was removed for 1982, allowing the fixed-skirt ground-effect setup to run lower, though the stiff suspension required to maintain skirt seal remained. Carbon-carbon reinforced brake discs and pads, first introduced on a qualifying-only basis on the BT49C, were used as standard equipment on the BT49D.
The car continued with the Ford Cosworth DFV V8 engine, which by 1982 produced around 500 brake horsepower — a figure that turbocharged engines from Ferrari, BMW, and Renault were increasingly surpassing. Ferrari's 1982 turbocharged V6 produced approximately 580 bhp.
The BT49D was one of several DFV-powered cars fitted with large water tanks at the start of 1982, ostensibly to cool the carbon-carbon brake discs. In practice, this water was drained early in races, allowing the cars to run as much as 50 kilograms under the minimum weight limit during the race itself. Under the rules as then written, coolants could be topped up at the end of the race before post-race weighing. The DFV teams, including Brabham, argued that their practice met the letter of the regulations and was justified as a means of compensating for the performance deficit against more powerful turbocharged cars.
Piquet won the Brazilian Grand Prix in a BT49D at the start of the 1982 season, but was disqualified after a protest from Renault and Ferrari that the car had raced underweight. FISA ruled that in future all cars must be weighed before coolants were replenished, effectively closing the practice. The ruling triggered a boycott of the fourth race of the season by most DFV-powered teams, including Brabham. Under pressure from BMW, whose turbocharged BT50 was now the team's priority programme, Brabham did not return the BT49D to racing until the Monaco Grand Prix, where one was entered for Riccardo Patrese.
Patrese won Monaco in a BT49D after a chaotic final lap during which several leading cars stopped. He then took a second place behind Piquet's BMW-powered BT50 at the Canadian Grand Prix — the BT49D's final Formula One race. The car was then retired in favour of the turbocharged programme.
The BT49 family, including BT49D chassis, has competed regularly in the FIA Historic Formula One Championship since 1995. In 1999, Motor Sport magazine tested a BT49D, recording approximately 530 bhp from a developed DFV at 11,200 rpm, though the championship subsequently introduced restrictions limiting engines to 10,500 rpm to control costs. The hydropneumatic suspension used in the BT49C specification is not permitted under historic regulations. Christian Glaesel won the 2005 FIA Historic Formula One Championship in a BT49D, and the variant continues to race in historic events as one of the more competitive and historically significant DFV-era machines.