The Lotus 99T is a Formula One car designed by Gérard Ducarouge for use by Lotus in the 1987 season.
After Renault pulled out of F1 at the end of 1986, Lotus signed a deal with Honda for use of their turbocharged 1.5-litre engine. Due to Honda's existing deal with Williams which allowed that team exclusive use of the 1987-spec RA167E unit, Lotus instead used the previous season's RA166E. As part of the deal, Lotus agreed to sign Honda's test driver Satoru Nakajima as teammate to Ayrton Senna.
Lotus also had a new title sponsor and livery, with the black and gold of John Player Special being replaced by the bright yellow and blue of Camel.
The 99T was the second Lotus chassis to be fitted with electronic active suspension after the team had experimented with the system on the Lotus 92 used in the first part of the 1983 season. The system's benefits of a consistent ride height with no pitch or roll in the chassis came at a cost, as the system added significant weight to the car (approx 25 kg or 55 lb), and also robbed the Honda turbo of approximately 5% of its power (the RA166E was rated at approximately 900 bhp (671 kW; 912 PS) with 1987s 4.0 Bar turbo-boost restriction). Ducarouge clawed as much performance back by spending many hours in the wind tunnel to compensate, although by the end of the season Senna was describing the car as nothing more than the previous year's 98T with a Honda engine instead of the Renault. The 99T was generally regarded as the bulkier of the cars that won a Grand Prix in 1987 with the Williams FW11B, McLaren MP4/3 and Ferrari F1/87 all regarded as better aerodynamically than the Lotus. Despite this, the 99T (especially in Senna's hands) was often among the fastest cars in a straight line.
