With speed factor on the left, it's too sensitive at higher speeds, and with the gas/brake linearity on the middle, they're also too sensitive. I don't have a G25 though. The only 2 cars with fine brakes are the Beetle and Charger SRT8. With these two you can really push a lttle bit, and they will just roll to the intersection.
EDIT: Just found a weird bug: Get a Viper, wait til it rains, put it on 6th, slightly push on the throttle and take your foot of the pedal, and the car will start to spin without touching the throttle :confused: Generally, when you push the throttle slighly, and then leave it, the cars accelerate to some speed. As it's a Viper and it's slippery, the wheels spin (untill it reaches 20mph) :lol:
I think that's one of the proofs that the physics are bad.