The McLaren MP4/2 was a Formula One car designed by John Barnard of McLaren for the 1984 season.
An iteration of it, the MP4/2B, was used in the 1985 season, and a slightly updated version, the MP4/2C, raced in the 1986 season for McLaren. It was closely based on the MP4/1E model that was used as a test car, used in the final races of 1983.
Like the majority of its competitors, the car used an all carbon fibre chassis. The car was powered by a TAG Porsche V6 Turbo engine, which was first used in the final few races of 1983, at the insistence of Niki Lauda, who felt that the new engine required race testing before a championship challenge could be mounted. The existing chassis, the MP4/1 was modified and strengthened to take the new engine and in the final race of the 1983 season, Lauda proved the car was competitive, running at the front of the field and challenging for the lead of the race.
Lauda was joined for 1984 by Alain Prost who had narrowly lost the 1983 championship to Nelson Piquet. Prost was made the scapegoat for Renault's failure and was fired, before Ron Dennis snapped up the young Frenchman in place of John Watson. Prost and Lauda proved to be a formidable combination. Both were excellent development drivers, and both gave technical feedback on the car and the engine which pushed the car's development far further than the other teams.
The MP4/2 was almost virtually unchanged in 1986 (with the exclusion of some tweaking in aerodynamics), while Prost was joined by Finn Keke Rosberg. By this time the Williams FW11 had overtaken McLaren as the best car; notably, the MP4/2's mileage was not as good as it was in 1984 although the fuel tank size in 1984 was 220 litres where in 1986 that had dropped to 195 litres. Piquet joined Nigel Mansell at Williams and the two fought a fierce internal battle, while Prost cleverly built up his points total and snatched 4 wins from under the Williams teammates' noses. His second world championship was won more by stealth than speed as by now it was clear the TAG Porsche engine was past its best.
For 1985, the MP4/2 was updated with cleaner aerodynamics and redesigned wings (to comply with new regulations) while TAG refined the engine. The suspension had to be redesigned after McLaren were forced to switch from Michelin to Goodyear tyres when the French company pulled out of Formula One. However, the competition had more or less caught up. Michele Alboreto (Ferrari) fought Prost for most of the season, until McLaren's greater reliability and their superiority in the high-speed circuits that followed told in both championships. Prost won his first championship with 5 wins, and McLaren claimed their second successive constructors' championship. Lauda retired from F1 at the end of the season, but not before adding a final victory to his tally in the Netherlands for the team.
The MP4/2 won 22 Grands Prix (Prost, 16; Lauda, 6), took 7 pole positions (Prost, 6; Rosberg, 1), and scored 327.5 points throughout its three-year career. It contributed to 2 constructors' titles and 3 drivers' championships, and remains the most successful chassis in F1 history.
Prost's MP4/2C was driven at the 2010 Goodwood Festival of Speed by Jenson Button.