Ground effect had been banned at the end of 1982, and so the car was built around a flat bottomed arrangement. It featured enlarged wings to try to claw back as much of the lost downforce as possible. René Arnoux had left the team to be replaced by Eddie Cheever, whilst Alain Prost was now undisputed no.1 driver. The RE40 was designed around his driving style, and he racked up many miles of testing to avoid the unreliability of the previous two seasons.

The RE40 was the first Renault chassis to be built entirely of carbon fibre. Construction of the chassis was outsourced to carbon fibre-specialists Hurel-Dubois, who had experience of the material through their aerospace background. The only part of the chassis not to be constructed in the new material was a small, aluminium nose section, known as the "crash box", that facilitated easy repair in the case of a minor accident. As Formula One use of carbon fibre was only a recent development, and following Didier Pironi's career-ending accident the previous year, the chassis was overbuilt to ensure strength.

Within the novel chassis sat Renault's, by now venerable, Renault Gordini EF1 turbocharged 1.5-litre V6 engine. The unit had first been introduced with the Renault RS01 in 1977, and was the first turbocharged engine ever to win a Formula One Grand Prix. Over the years the engine had been uprated and subtly redesigned, and the twin-turbo (one per cylinder bank) evolution within the RE40 produced a claimed 880 bhp (656 kW). However, the turbochargers themselves were to prove the RE40's weakness in 1983, and on numerous occasions turbo troubles ended Prost or Cheever's race. Alain Prost later recalled that "that year there was a good turbo to have and a bad one. We had the bad one".

...
Wikipedia