McLaren MP4/8

Information

MP4/8B test car with Lamborghini engine.
In 1993, McLaren reached a deal with Lamborghini to use their engines in 1994. So this chassis, originally a spare tub, was modified and fitted with Lamborghini LE3512 V12 engine which was used on Larrousse then. The car was painted in pure white and was tested by Ayrton Senna and Mika Häkkinen at Estoril and Silverstone.
With adjustments advised by Senna, the MP4/8B with Lamborghini engine ran well, even faster than the original MP4/8 with Ford-Cosworth V8 engine. Many thought if McLaren had used Lamborghini engine earlier, they should have won the 1993 titles. However, even before the Lamborghini tests, McLaren already started to negotiate with Peugeot, and this led McLaren to give up Lamborghini engine, despite it showed huge potential.
In the end, McLaren switched to Peugeot in 1994. Although Peugeot achieved great success at sports car racing at that time, Senna didn't have much faith on these engines in F1, and this was a part of his departure to Williams. And his concerns were proven to be right, in 1994, MP4/10 with Peugeot didn't won a single race, and McLaren ended contract with Peugeot after only one season.