shopping carts, if you have to set your gas and brake pedals to X and Square every time you start the game, just to make them work, that could be the problem.
If you read the MC2 manual, it tells you to set the gas and as right analog stick up and brake as right analog stick down in the game's controls option screen.
I had a similar problem when I first got it.
I was like, "wtf, where is my throttle control? is it just gas on/gas off?" Just cuz I was setting the controls with the wheel program button instead of the options menu.
HOWEVER. I did notice that in GT3, if you hold the e-brake down and rev your engine with the pedal, the turbo pressure gauge is maxed out before the pedal goes through it's full range of motion.
With the pedal hovering an inch over the plastic base of the pedals, the turbo pressure is just maxing out. That and the squeaks are the only problems I can detect.
Apparently the wheels used to squeak like mad but they recalled them, but they obviously didn't fix the pedals.