I remember playing a few racing games like 12-15 years ago, not quite sure.
First: A sci-fi racing game, 3 diffrent planets that have 3 levels each, first planet is desert-ish, second winter-ish, third volcanic.The game had a shooting mechanic where u shoot when pressing space, it shoots where your car is looking. I think I played it on pc, windows xp. There were quite a lot of diffrent vehicles you could get. A starting car was a three-wheeler red car, the very last vehicle, the fastest vehicle was flat hovering vehicle, it's color was purple-ish, the vehicle before it was a heavy one, which was slower, but also hovered, it couldn't be pushed around so much and when shot it wouldn't sway to the side as hard and it was yellow.
Second: Don't have too much info on this one. I think there were power-ups like boosters n stuff. Its also a sci-fi racing game. It was quite intresting, had more maps than the "First" game I was talking about. These are two diffrent games tho. I think when at the start of the race, when the countdown gets to 1 sec then press the accelleration button to get a speed boost for a few secs for a headstart. I don't remember hovering cars, only with wheels. There were quite a lot of jumps n stuff. I think you could upgrade your cars, idk, maybe not. Now that I think about it, you could look at it like this: Blur, but sci-fi and in volcanic/winter planets. It had multiple gamemodes: Singleplayer Career mode, Single Race (stuff like these usual racing games), Multiplayer had Soccer Mode, Splitscreen Racing and one more I don't remember, I don't believe it had online multiplayer, but at the time I didn't really have internet so I didn't care. Actually the game had more similarities to Wipeout (1995), but I tried playing it and no it was not it.
I guess both these games would have the tags: Sci-Fi/Racing/Vehicular Combat.
One quick detail: The games graphics,I believe, looked similar to Carmageddon 2: Carpocalypse Now. So I think they came out during a similar time.
These aren't the games: AIM series, Twisted metal, Death race, POD,sky race, cyberline, Wipeout...