I've recently started playing again. The physics are broken unless you tune your car just right.
Where in GT, you usually tune to influence oversteer, in shift 2 you have to tune to influence understeer. Try setting a harder suspension in the front and a softer suspension in the rear. Little front downforce (speed in front corners in rear) things like that. It usually helps the iffy physics...
Although if you touch another car 9 times out of ten you're still gonna have a bad time.