Simple and fun
It's a nice engine. However engine isn't fun for long.
Nice work on the solar halo, that was a nice touch.
Somethings to improve the game engine/ gameplay would be a wrong way indicator, a player position indicator or a score by meters/seconds to see how far ahead or behind you are.
I also agree that the track could be more visable.
If you really want to take this game idea to the next level, try some brighter level designs and powerups (boost would be great)
But over all nice concept and good work with the 3D