Blur: not winning any fans

I've heard from many that the single-player mode of Blur is easy. I beg to differ.

I'm now stuck on the fan races. I've completed all the races with a bronze or above, but I need to get some sort of "X5 multiplier" on one of the races in particular, and I don't recall being told how to do that. I may need to look at an FAQ, for shame.