The BT46B generated an immense amount of downforce utilizing a fan, claimed to be for increased cooling, but which also extracted air from beneath the car.

The car only raced once in this configuration in the Formula One World Championship—when Niki Lauda won the 1978 Swedish Grand Prix at Anderstorp.

This was due to the difficulties of packaging the large, powerful Alfa flat-12 engine and the fuel it required to complete a race distance.

It was intended to compensate for the weight of the engine and fuel and allow the Brabham team to take a large technical step forward as well as to improve safety.

It featured inbuilt pneumatic jacks fed from an external supply of compressed air to lift it off the ground for tyre changes during practice.

[10] The most radical feature of the original car was its use of flat plate heat exchangers mounted flush to the surface of the bodywork in place of conventional water radiators.

The absence of standard radiators allowed Murray to compensate somewhat for the large engine and fuel tanks and produce a relatively light design with a low frontal cross section (important to reduce drag).

Cox was invited by the team to discuss his calculations, pointed out what he believed to be fundamental errors in the concept and concluded that the idea could not be made to work.

After the winning debut and subsequent withdrawal of the BT46B "fan car" at the Swedish Grand Prix, the Brabham team completed the season with the standard BT46s.

Ground effect had the great advantage of being a low drag solution, unlike conventional wings, meaning that the increased cornering ability was not compromised by a decrease in straight line speed.

[13] In 1978 Lotus ironed out the reliability problems and further developed the concept from relatively simple sidepods with a wing profile into full venturi tunnels under the car.

As soon as they appeared at Zolder, the black and gold Type 79s of Mario Andretti and Ronnie Peterson outpaced the opposition by a comfortable margin.

He also realised that the Alfa Romeo flat-12 engine used by Brabham that season was too wide to permit the Venturi tunnels needed for really significant ground effect.

The 2J had two fans at the rear of the car driven by a dedicated two-stroke engine to draw large amounts of air from under the chassis, reducing pressure and creating downforce.

[14] The contemporary Tyrrell 008 designed by Maurice Philippe had been built with a small fan fitted at the rear and driven from the engine's crankshaft.

[18] Cox produced the overall layout for the car, utilising the cooling properties of the fan to be able to argue that this was its primary purpose, thus satisfying the regulations.

[20] The two modified cars were prepared for the Swedish Grand Prix at Anderstorp on 17 June 1978, for Niki Lauda and John Watson.

When not in use, the fan was covered by a dustbin lid, but it soon became clear what the modified Brabham was intended to achieve: when the drivers blipped the throttle, the car could be seen to squat down on its suspension as the downforce increased.

Once the slower Didier Pironi dropped oil onto the track and with both major front-runners out of the race, the remaining Brabham was in a class of its own, seemingly unaffected by the slippery surface.

Lauda passed Andretti around the outside of one of the corners, who dropped out shortly afterwards due to a broken valve, and went on to win by over half a minute from Riccardo Patrese in an Arrows.

Originally intended as a non-championship Formula One race, without FIA sanction it was instead run in a time trial format, with victory going to the fastest single lap recorded.

The standard radiators were replaced by units from a Volkswagen Golf mounted behind the front wheels out of the airstream in a region of positive pressure.