I also noticed (but I may be mistaken) that the smaller 'ability range' setting , the more agressive driving style a driver represents.
When I set my 'ability range' to 90, I noticed that my driver would brake sooner before taking a corner...also accelerating when leaving corners and making for long straights was slower.
When I set 'ability range' to 62 , I saw a noticeable difference...my driver would brake later(which, on wet surface, sometimes resulted in leaving the track ) and his acceleration was much more efficient as he would step on it even before leaving a corner, so I was able to get much better results on tracks like Hungaroring or Monte Carlo
@Jackal
Your explanation seems to be quite sensible. Now all the pieces of this jigsaw start to make sense to me