Interesting concept similar to what my co-worker thought of. He refered to it as the air sprayer effect, basically paint is pulled up when air pressure is passed over a straw creating a vacuum on the straw. Since the highest airflow is going over the car, having the end of the exhaust pipe end in the direction of the top air flow of the car and just slightly into the air flow would create enough vacuum with out slowing the car down more than the benefit.
If you have a way to check instant MPG, couldn't you throw an extra battery + inverter (need a higher grade one for motors) in the trunk, hook all the hosese etc, and check MPG change at steady speed with vac on/off with out changing any draw on the engine etc? Really would love to see some results
. I could see those with the alt delete adding more batteries for a vacuum lol.
