Originally posted by JWard:
Riding with the tailgate up creates a "bubble" of air in the bed, so the air flows over it. Ride with it down and the bubble is gone and the flat back of the cab creates drag.
Hop in the back of a p/u and run her up to 65mph and tell me if you still believe this. :p
I tried the tailgate up/down experiment. The tailgate down resulted in a bit better mpg due to reduced drag (quite the contrary to the "bubble theory").
But, I'd rather have the better structural ingegrity of the tailgate up and not have a 75lb piece of metal flapping around on the back of my truck at highway speeds endangering other motorists (came to my senses after hitting some bigger bumps and watching the gate jumping about).
IMO, the "bubble theory" was cooked up for liability reasons (see above).
BTW, the compressor does shut off at WOT on our cars.
