If it pulls to the left as soon as you start driving, it is most likely one (or more) of the wheels are slightly rotated in your actual mesh, but you may be able to fix it by changing the wheel offsets in the “Vehicle Setup” tab of the vehicle defaults (just below steering angle):
You can try adjusting the “Individual offset” for certain tires there, however the best way would be to fix the mesh in your 3d content creator tool (will be either the wheels, or wheel bones if you used them, are rotated slightly, causing problem, or possibly the entire car) as will most likely cause you headaches later on if you have to constantly adjust values as you go.