This pisses me off too. I purposely always get rammed into and nudged off the track by idiots, it appears that even the higher ranked players do it. Trailblazer & Rally are the only 2 non-contact races you can do in the online Pro Tour.
With the contact races, a usefull tip (previously mentioned by Phanton Anubis) is to just hang back a little at the start of the race and 90% of the time 1-4 will smash into each other at the first corner then you can just whizz past (while laughing at those idiots) and then have plenty of time & space to catch the leader(s).
I too, once I have reached level 30 & got the Rush Hour achievement will never touch this game again, not online anyway.
100% Completed Retail Games (111) - Including all DLC