Matt I have to agree with you big time on this one. My 85 3/4 4X4 Ram I think
got a little less mileage with the tailgate down. (And that muther drank
premium gas like it was water) Realistically it was hard to notice, but I
think it was a consistent half a MPG for highway miles. Consumer reports did
a long term test a couple years ago and claimed that it lowered mileage as
well with the TG down. And I've heard reports that at highway speeds in the
rain with the tailgate down, without the separated air bubble effect you run a
much higher risk of having the rear wheels hydroplane on you becaus it
actually has a lifting effect. Hmmm.. do they run without tailgates in the
Nascar Truck series? I'm not sure. Don't watch it much.. Just my .0005 cents
worth...
--- Matt wrote --
big snip---
The subject of the tailgate up or down and its effects on fuel mileage and
drag has always been a hot topic . Most people are either in one side of the
fence or the other. I have had 3 trucks, 84 Ram, 85 F-150, and now the Dak.
I have experimented with the tailgate down/up and have never seen any
increased MPG with it down.
Lockhead Aircraft did wind tunnel testing on trucks in the 90's with
tailgate up and down and actually found that leaving the gate up created
less drag than putting the gate down!! A "separated air bubble" forms in
the bed of the truck at highway speed which lets the air flow freely over
the tailgate.
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