You need to remember, that once you pass the low sensitivity zone, your control will work pretty much like a digital input device, that is on (@ full lock)/off (@ the edge of the low sensitivity zone).
If you want a smooth liniar response throughout the whole range of motion that your controller has, then set the controllers low sensitivity zone to 100%. 20 degrees max lock is very suitable to a 100% low sensitivity zone.
If you like you car more twitchy, then reduce the low sensitivity zone. 2% will give a very twitchy car. Say your controller has 270 degrees of travel, 135 degrees to each side. 2% is 5.4 degrees, or in plain english, you can move your controller 2.7 degrees left or right before it acts like an on/off switch.
It's only after we've lost everything, that we are free to do anything.