3D racing game with flying cars and UFOs.
 

About 2 to 5 years ago I played a 3D racing game that featured cars that could extend wings (probably by pressing the space key). The cars didn't fly as such, but could glide. Instead of racing in a car, you could also fly some kind of a UFO, which could shoot other UFOs or cars. The game was still under development, but was quite a lot of fun.

I think the game was made with Unity, since I could play it in the web browser, but also download a stand-alone executable. I think the game also featured some multiplayer capabilities.

It sounds a lot like the SNES game F-Zero
Maybe the PC port for it?
Another possible shot - Zone Raiders

My guess would also be Zone Raiders. I remember playing that game as well, and you could extend wings in order to glide a short distance. F-Zero does not have a gliding function.

Actually, since the OP was talking about something a little more recent, I think it might've been Nitronic Rush.

http://nitronic-rush.com/

Thanks for the answers, but it's none of those. It didn't have old or retro graphics and the race tracks were on a barren landscape (kind of like Mars).