Courses are
coyote rage
raingod mesa (the demo track)
the mud pool
the rock hopper
the grizzly
dust devil
the tenderizer
sidewinder gulch
Unlocked most of level 3, there are various versions of "dust devil" which involve the time of day. The sunset version is gorgeous but hard to see where you're going, you have to know the track, also a night time version with moon and stars, looks great but again really hard to navigate as you and the other vehicles don't have headlights, the stars reflect in your bonnet in the in car view.
I suspect in level 4 the other tracks have these time of day variations. The game is getting ridiculously hard at level 3, god help me if i ever reach level four.