I like really like the effects when speeding up. I think by far my favorite level was the last one since it allowed you to go really fast (1450!). I wish there more more levels like that one where you just feel powerful having difficulties to steer because of your sheer speed! The level select doesn't quite work for my screen tho, maybe the anchors aren't set right...
All and all great concept and nice execution for the limited time you had!