From the impressions I've gotten of the game, the buttons aren't pressure sensitive! Would have certainly been a good option! If you wanna check out a game with pressure sensitive compatibility, check out Tokyo Racer Zero (the street racing game!) I've got that game and it certainly does have that option inbuilt into it!
In regards to GT3, just tap the buttons to maintain your speed around corners or what-have-you. Or you can always oversteer if you've got a RWD car :D
*crash navigation sig removed in memory of Possum Bourne! RIP!*