Can anyone tell me if driving with the tailgate down on my truck help or hurt fuel mileage? I have a 2002 Chevy Silverado 6.5 ft bed with aluminum toolbox in the back mounted directly behind the rear window. I have heard yes and no answers about this in the past but have never seen anything done on it like a study or anything official yet. If anybody here can help me answer this question, thank you in advance, John......
