How to improve fuel economy with a tonneau cover
 

Via autobloggreen.com ...

How to improve fuel economy with a tonneau cover

Full details of their methodology is available, which is nice. (Have to go to the manufacturer's site to read it.)

snug top
 

Darin,hope they didn't go broke buying and burning all that fuel.It's a great thing for them to have done all the testing.And 1.3 mpg at 45-mph really does speak for even better mpg at higher speeds.I've done your famous self-administered head-slap for just getting around to looking at this post at such a late date. Its a significant contribution,should really help the pickup owners, glad I got to see it,thanks much for posting it.

In college, I had a 1995 GMC Sonoma (S10 clone), with a regular cab and short bed (4cyl, 5 speed, 2wd-- totally stripped-down model). I had a tonneau cover the whole time I owned it, and I definitely got several mpg less at highway speeds when I didn't have it on (not that often, but I definitely could tell). With the cover on, and normal driving, I got around 30mpg at 75mph. My all time high was 32mpg, without really trying, and before I ever heard of hypermiling.


But yeah, to keep on topic, keeping the tailgate up is better than down, and a tonneau cover is better still. It's not as good as fashioning a cap into a pseudo-kammback, but every little bit helps.

Actually, this is one of the few things that was done right on Mythbusters (since there were no explosions involved). Tailgate up is, without doubt, better than tailgate down. With the tailgate up, a vortex forms over the bed that sort of acts like a kammback (though not as effective, being normal-pressure air currents). That current does not form with the gate down; driving like that makes your wake bigger and more turbulent.

Yes, it's counterintuitive.

The SAE also has a published paper that proves tailgate up is better.

Wow!

They found out what I found out eight years ago. In a 70/60/city circuit I got a 1.5 MPG improvement.

Anybody wanna buy a nice ARE tonneau?

Nice MetroMPG. I learned a lot of information with this thread. I hope that I can improve fuel economy with a tonneau cover. :D

If a tonneau does not help your pickup,you're doing something wrong.

what if you were to place a piece of sheet metal from the middle of the bed,to the top of the tailgate? The low side would be at the bed and the high part would be at the tailgate.

If you are thinking about it sloping up like a big spoiler it probably won't help mpg. Although, I believe Chevrolet did some testing and found a half tonneau covering the back of the bed was better than a full tonneau for reducing drag. It would have been level with the top of the bed though.