Been trying this game, it is pretty addicting. But I can't get much past 4th in the first map on supersonic. I'm best at the second, but not much better there.
I thought I was quick, but I guess i'm not heh.
I had this problem for a while. You just have to approach obstacles differently. For example: The 3 rods that go through the track are usually dodged at first by going to the right, then left then right. At higher speeds this is impossible, you have to just do a 360 to dodge all of them. Experiment with all the different obstacles and how you can dodge them effectively.