I gave rFactor a blast earlier and I was awful. Couldn't stay on the track for more than 30 seconds around Brands Hatch Indy circuit.
What settings you using? If you've got a Logitech wheel, you need to change one of the settings in to minus figures (it's on a slider, can't remember it's name).
It's a good game, but you will need to customise it for your wheel. If you are trying to pad it, get a wheel.