For reference, I seem to recall that hitting someone with a car using Driving is a base Weapon:3 attack.
This may fall under the proviso against using Falling rules to score huge piles of damage on people by throwing them off things. Using the vehicle as a projectile may simply be a justification for transmitting as a ranged attack the incredible amount of damage you can normally only do in melee combat.
But... people use solid objects to hit people better all the time, in real life and in fiction.
At the very least you could Declare (using your Might) the aspect Projectile Car and then free tag it for a +2 bonus when throwing.