Days Of Thunder is not a typical movie score. It sounds rather like pop/rock music with lots of electric guitar (actually too much for my liking) and drums, but without vocals. Most of the cues are rather short. The music is not ingenious, but probably works well with the movie.
Especially in “Main Title”, Hans Zimmer plays a lot with pitch shifting in his synthesizer sounds, probably to simulate the Doppler effect of passing fast cars, which is an interesting idea. The synthesizer sounds are sometimes not really convincing, by the way. The one exception is in “Wheelchair Race”, where two different sounds are masterfully blended gradually into one another. “Car Building” would be a formidable track, if the last minute had been omitted... “Kamikaze Drivers” suffers tremendously from an overly used, repetitive drum pattern. In “Cole & Claire”, the music comes to rest for a while, and becomes quite enjoyable for once. “Drafting” is reminiscent of Zimmer's score to Green Card (very similar sound, partially same melody).