Blizzard should implement ground vehicles that have some sort of physics to them (drifting, acceleration, decceleration, pushback on collision). This is in fact already existing in a very limited fashion: Vehicles can only turn at a limited angle per second, even if you turn much faster with your mouse.
Then give those vehicles a few abilities (techonlogy for that exists already) which can only affect other vehicles (so they aren't used in actual combat). Those abilities could be bananas (MarioKart?
), pools of oil/slime, nets, slows, etc.
It would open up a whole lot of awesome gameplay. I know I would race all day