If a car and a bowling ball were thrown off a 100 foot cliff at the same time which would hit the ground first?

All things fall at the same acceleration so they would accelerate at the same rate. From 100ft they would hit at roughly the same time, possibly the he ball would hit a little sooner. The weight difference would have no effect. Any difference is due to air resistance. The car has more and will therefore fall fractionally slower. If they fell in a vacuum they would hit at exactly the same time (no air resistance). If they fell from a much higher height (not in a vacuum) the ball would hit first as it has a lower cross sectional area so would have less air resistance and therefore a higher terminal velocity.