The Honda RA099 was a prototype Formula One racecar, commissioned by Honda, designed by ex-Ferrari and Tyrrell designer Harvey Postlethwaite and built by Dallara in 1999. Its purpose was similar to the one surrounding the Toyota TF101 of 2001, in that it was supposed to be a working test car used in preparation for a full-scale assault on Grand Prix racing in the following years.

Harvey Ernest Postlethwaite was a British engineer and Technical Director of several Formula One teams during the 1970s, 1980s and 1990s. He died of a heart attack in Spain while supervising the testing of the aborted Honda F1 project.