My initial entry into the wonders of racing game music was Ridge Racer for PlayStation. Just excellent, pumped tunes in there by the sampling masters Shinji Hosoe, Ayako Saso among others. The essential crank-the-volume racing music.
Racing Lagoon has always been a blast because of the various forms of jazz infused tunes with electronica, acid, funk and lounge goodness. I don't care much for the "rockier" tracks on there but most of the material across the two-disc set is an absolute listening classic in my book. Racing Lagoon has always had a plush goodness, a velvet smooth sound that has not been tried elsewhere.
Automodellista is an interesting one because it's both lounge jazz (most looped) and heavy rock and electronica. I prefer the menu and garage musics, but some of the racing tunes are funky (Cruisin', In The Light, Opaque Air) albeit repetitive on the disc release.
Gran Turismo, the album release, was always nice to relax to with Isamu Ohira's jazzy menu themes. To American gamers, the Japan-based disc releases always confused me but lured me because of the two-faced side of the disc; some jazzy and some instrumental rock (with a saxophone or some other cheese like GT1) without any of the licensed crap. As far as the album releases, GT2 got a little cheap (Ohira had no orchestra, Ando was nonexistant), and GT3 was not very catchy (didn't care for any of Daiki Kasho's noisy tracks). When you get Ando on the project, you can only expect jazz-fusion and most of it good stuff.
F-Zero; original tunes were excellent, classic. F-Zero X was flat, the Guitar Arrange Edition was what "X" should've been, and F-Zero GX was fantastic. Of course, I throughly enjoyed the "fusion" arrangement album.
Enthusia continues to impress. Anything with Shusei Murai on piano is enough to keep me listening. Actually, my favorite tracks from the album were the outstanding jazz arranges on the end second disc which really came out of nowhere. This one also came by surprise because of the different sounds; rock and dance electronica with the occasional jazzy interludes. Enthusia stole the thunder from the Gran Turismo 4 soundtrack which came out within weeks of each other, which had me disappointed.
Other favorites: Driving Emotion Type-S employs "Street Fighter EX+a" standards by the same crew who did that game (Hosoe, Saso, Aihara) with an overall fusion sound in there. "A light turn" and "Best tone" are eternal artist favorites. Sega Rally is a solid Sega rock soundtrack, Daytona USA is self-explanatory.
Hope I didn't forget any...