It states that all parts of the vehicle must travel between the 2 cans but what if the vehicle is taller or wider above the height of the cans. Would the can bonus still be awarded?

The vehicle may be taller than the cans and be eligible to receive the can bonus. As per rule 4.d.vii.(10), all parts of the Vehicle must travel between the cans. If any part of the Vehicle passes above one of the cans, then the bonus will NOT be awarded.