Ok.. here goes.. no solution.. just pinpointing the problem.
Just let yer bud stand still on a straight or in the pits, hit Ctrl-F for framerates, now start turning the wheel to either end and see if he is losing frames per second.
I've had that with the G25 for ages now, tried to find out what it was, updated nearly everything, but i still encounter it.. sometimes worst then other times.... not many ppl with this problem either but lately i haven't really bothered to look for the solution either.
It might have to do with the USB ports, mine says it's got 2.0, but with the saitek r440 with 1.0 i had no problems at all... it's weirdness and dear Shawn ([SJ]Instig8r) has spent hours with me trying to sort the problem.. not really found a solution except setting up the graphics card correctly for different games (making profiles)... i dont notice it alot now.. (updated to a 3.0ghz (single core double threads) but it's still there, just not that overwhelming.
Woof ~ Woof