Some transmissions are just slower than others it seems.
You might want to edit the line in eg. vehicleset_pc_custom_wheel.xml :
in the controller file you're using, then re-select it and hit '2' to reload its defaults in your profile. This makes it shift to neutral as soon as you take it out of the current gear and - at least for me - makes the shifting time a lot more predictable on the low end cars.
WIP no hands/wheel mod at: