My preferred setting is zero. I adjusted it to zero (default is 7). I don't know what the game did with that, but it's definitely not zero. The deadzone has nothing to do with steering lock, or with car setup. Well, if there's nothing weird going on, steering sensitivity does what you say it does. Controller damping slows down direction changes, so you can't turn the wheel unrealistically quickly from left to right. These things can have an influence on the perceived deadzone, but they shouldn't change the actual deadzone.