In 1986, the car won first time out in Brazil with Piquet, before Mansell laid down a title challenge with four wins.

Patrick Head stepped up and managed the team until Williams returned late in the season.

This may have caused the in-fighting between the two team mates, and the lost points helped Alain Prost take his second world championship.

[3] Reportedly, both Nelson Piquet and Honda, whom it was rumored were paying the bulk of the Brazilian's USD$3.3 million retainer, left Australia angry with Head and Williams Management.

Honda were now supplying Lotus with the same engine supplied to Williams (though Lotus used the 1986 RA166E engine rather than the RA167E 1987 engine used by Williams), which helped Ayrton Senna challenge consistently, but the FW11's superiority told, and Piquet finished in the points (mostly on the podium) in every race other than San Marino (where he had a terrible crash at Tamburello during Friday practice, and he emerged with only a sore ankle, and he wanted to start the race but was prevented from doing so by F1 Medical boss, Prof. Sid Watkins who told him "You have a concussion, you can't race"),[5] Belgium, and Australia, and he was champion.

As for Mansell, he scored six victories including a memorable come from behind win at the British Grand Prix at Silverstone, passing Piquet for the lead with just 3 laps remaining.

Piquet's third championship was assured after Mansell had a major crash during practice for the Japanese Grand Prix.

Piquet would start from the pole and win the race from the Lotus of Ayrton Senna, with Mansell unable to keep pace finishing 3rd.

Honda were unhappy with Williams management for allegedly not honoring the number 1 status contract of 'their' driver Nelson Piquet.