Nfs shift uses hardware acceleration !!!

[Hell Hound]

Just because physx has mainly been used for effects so far doesnt mean it cant be used for more, its a full physics API with all the tools necessary to do what the OP claims,

Scalable terrain fedelity

Delivers physical landscape accuracy and genuine surface reaction for true environmental experiences

http://www.bfgtech.com/physx/bfgphysx.html (under features & benefits tab)

If your tires are not warmed up you may loose a second or two or If a piece of rubber is on the track and you drive over it you will feel it in your tire's.PhysX has potential.