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Mar6-12, 03:39 PM
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Quote Quote by maximiliano View Post
Accelerating the extra mass on flat; accelerating mass against gravity and wind drag due to the larger vehicle surely are #1 #2 and #3..??...and probably (just guessing...but someone would have to really do some convincing for me to think otherwise) account for 80+% of the observed reduced mileage per gallon of fuel with a SUV vs passenger car.
What do you mean by extra mass on flat?

I have an "over the road" trucker friend (interesting business by the way). He says he gets, on flat ground, 11-12 mpg full (50,000 lb load). He gets 12-14 empty. Now, that's only a ~15-25% difference....and of that, how much is NOT due to accelerating the heavy load (thus is caused by the increased road-tire friction)? I don't know...but it seems like most of it is due to the acceleration of mass. Tires matter....but if you're keeping them at a good pressure (I go 40-42 psi on trips), just can't imagine that's where the weight, by itself, gets ya. Maybe I'm off on that..... I'm open to evidence.
Can you be a little more specific and clarify what you said? Are you saying that without a load, he gets 12-14MPG while without a load, he gets 11/12MPG?

I'm in a hurry at the moment, but it would be necessary to know exactly how much a truck weighs by itself. A situation with a semi would be more complicated because the aerodynamics are, I assume, considerably worse than a passenger vehicle which would cause wind resistance to be a greater factor.