At least one noticable change in the physcis between GTR and GTR2. When slowing
(lift throttle) or braking, and the rear end steps out, you can steer inwards
to cause the front end to plow, to correct the oversteer (driver induced
understeer). This rarely worked in GTR, but it works well in GTR2.

For acceleration, normal counter-steering (outwards) and throttle modulation are
still required.

For some real racing cars that don't have downforce, when cornering at very high
speeds that require full throttle to maintain speed, a bit of induced understeer
can help stabelize a nervous car. Some players did this with Grand Prix Legends.