It used a BMW four-cylinder turbocharged engine tilted over on its side to allow a clear supply of air to the rear wing.

Brabham's tall, relatively heavy straight-four BMW M12 engine was particularly difficult to package to allow a good flow of air to the rear wing.

Designers in the 1950s had addressed the same problem of reducing the car's cross sectional area by tilting the engines around a vertical or longitudinal axis by a small amount.

Examples include the 1950s Kurtis-Kraft, George Salih and Quin Epperly's Championship Cars, and Colin Chapman's Formula One Lotus 16.

[3][4] Both the Brabham team and their gearbox supplier Weismann lay claim to the idea of doing this with the tall BMW engine in order to create a car with very low bodywork that would allow a large supply of air to reach the rear wing undisturbed and create more downforce without harming the straight line potential with high drag.

Although the team had been the first in Formula One to make use of carbon fibre composite panels in the structure of the car in 1978, Murray had been reluctant to design a fully composite car until he understood how it would perform in a crash: he eventually persuaded Ecclestone to finance a fully instrumented crash test of a BT49 chassis.

[2] At the end of 1985, Piquet left Brabham after seven seasons and two world championships, joining Williams which made him a much better salary offer.

The team scored just two points all season, both by driver Riccardo Patrese with sixth placings in San Marino and Detroit.

During qualifying for the Italian Grand Prix, Warwick and Patrese were the 3rd and 4th fastest cars through the speed trap on Monza's long front straight (behind the similarly BMW powered Benettons of Gerhard Berger and Teo Fabi).

The rather tall BMW [engine] had to lie down so far it produced a heavily offset crank needing a special gearbox and drivetrain, and what I did wrong was to try to do it in the time available.

"[8] Murray also stated in an interview towards the end of the 1986 season that despite the BT55's record, he still believed in the lowline concept pointing out that the car's problems were engine related.

The very successful 1988 McLaren MP4/4 is usually said to have been based on the BT55 concept, but that has been disputed, and that it was primarily a development of its predecessor, the Steve Nichols designed MP4/3.