I also use a gamepad.. logitech wingman rumblepad
Logitech provide the "Logitech Profiler" software which allows you to tweek some settings.
[Logitech Profiler]
Axis Properties ->
Low Sensitivity - I set mine to LOW
Dead Zone - I tested and found by adding about 3% - 4% helped
Also in the simulator..
[ Live for speed] - is there any other?
Controls ->
Wheel turn - I reduced mine to 90 degrees which again, helped
IMHO:
The gamepad is better than keys and mouse but is a compromise over using a Wheel.
The major problem with a gamepad is over-correction when steering; because the stick is small it's so easy to snap the wheel in the opposite direction and spin off. So I tend to give other online racers a wide birth out of courtesy!
I also give hand signals but that is another story.
Andy.