We like to create a wiki page about controller and best settings of them.
So tell us as a comment below what kind of controller you use and what your personal settings for steer sens, speed sens, dead zone, axis and buttons are.
Don't forget to calibrate your controller first!
An example:
Logitech RumblePad
Steer sens: 0.100
Speed sens: 0.100
Dead zone:0
Axis 0 for left/right
Button 5 throttle/ button 7 brake