During my weeks of racing atm all seemed fine but after getting into the higher ranks the difficulty of the npcs goes from stupid to extremely cold and calculating to the point where if your not blowing past first place they will do everything they can to stop you and no one else.
When your in the lower rating brackets they will use items and take what they can but as I learned later they start saving items for you and avoid using them on fellow npcs, skip items if they know you can benefit from them (removal with stam regain) and avoid taking items so you cant acquire the speed/stam boost powers entirely that is 2nd in line.
Bottom line is they need tweaked. They are not human and therefore shouldn't act like major douches every race just to focus on you out of the crowd.
Big difference between hard and cheap in terms of difficulty.