As of now when using mouse the way the steering wheel works is the opposite of how every other game does it. Its easy at steering wheel center and heavy when steering further left or right.
It should be heavier at center and easier the more you steer. This because when at fast speeds (which we can reach in ARMA3) you wont have an easy steering center that can make you oversteer too easily, and therefor you can make much finer movements which is needed when going fast. This is standard in any well done game with cars.
This is alpha, but please look into it.
ARMA2 before its steering update had it perfect in this particular regard.