Depends on the race. In the Impreza time trial, I was getting about 25 fps at 1024x768 with 2xAA and everything set to high quality. But with the motion blur turned on, it's actually feels smoother than that.
It's very demanding, but looks incredible.
Core i5 2500K @ 4.8 GHz || 16 GBs 1600 MHz DDR3 || Saphire Radeon HD 7970 || Dual 128 GB SSDs