Damn impressive!
For your first game, this is really damn good!
All you really need to add in are just some smaller aspects... different cars... maybe a set number of cars, and a place indicator... manual cars with proper gear ratios (a family 4 door at a 250 top speed is a bit much :-P).. different road surface, for the first 2 minutes I avoided the rocks because I didn't think that'd be a great idea hitting them going that fast.. maybe be able to upgrade your car with performance mods or body kits (i'd love to see a grocery getter with a kit!)
The biggest thing I could suggest if you plan on sticking with this idea.. try to come up with something original... it seems like everything I see on here either ends up like DragRacer or CreateARide... if you could come up with new and different you could definately grab yourself a spot on the front page...
Good job man, how's that for some positive encouragement!