Bed toolbox as partial tonneau cover

[aardvarcus]

In addition to the factory cover, don’t forget the Avalanche also has a seamless cab to bed transition and I believe it has higher bedsides, but that could just be an illusion.

I put a Backflip full tonneau cover on my 2001 2500HD extended cab short (6.5') bed. With the 8.1L engine, Allison Automatic, 4.10s, 4x4, 285/70R17 Michelin M/S 2 on factory 17” alloys, I can squeak out 14MPG with very conservative mostly highway driving. Previous best prior to tonneau was 13 MPG, but that isn’t A-B-A so take it with a big grain of salt. Around town is 11.

[aerohead]

Originally Posted by aardvarcus

In addition to the factory cover, don’t forget the Avalanche also has a seamless cab to bed transition and I believe it has higher bedsides, but that could just be an illusion.

I put a Backflip full tonneau cover on my 2001 2500HD extended cab short (6.5') bed. With the 8.1L engine, Allison Automatic, 4.10s, 4x4, 285/70R17 Michelin M/S 2 on factory 17” alloys, I can squeak out 14MPG with very conservative mostly highway driving. Previous best prior to tonneau was 13 MPG, but that isn’t A-B-A so take it with a big grain of salt. Around town is 11.

Thanks.I should not have inferred that all the drag reduction was linked solely to the tonneau.I went back and 'accurized' my comment.
The Avalanche/Escalade/Ridgeline must get a little benefit from their cleaner flanks.And the lofted the bed rails should reduce the vortex in the bed.
Some of the concept trucks have very high rails with respect to the cab roof.
It's a good thing and perhaps truck buyers will embrace the 'difference.'

[Frank Lee]

Some of the concept trucks have very high rails with respect to the cab roof.
It's a good thing and perhaps truck buyers will embrace the 'difference.'

I think it is a very BAD thing; this crazy pishing contest to see who has the tallest truck has resulted in bedsides so tall that even a 6'4"er can't simply reach into the box to retrieve stuff. You have to hop in- oops, can't do that any more either, you have to put the LADDER attached to the tailgate down to climb in. And then there are all the munchkins that can't even make it into the cab without running boards- can we say extraneous height increase? Didn't running boards go away in the 30's?

[ijames]

Originally Posted by Frank Lee

I think it is a very BAD thing; this crazy pishing contest to see who has the tallest truck has resulted in bedsides so tall that even a 6'4"er can't simply reach into the box to retrieve stuff. You have to hop in- oops, can't do that any more either, you have to put the LADDER attached to the tailgate down to climb in. And then there are all the munchkins that can't even make it into the cab without running boards- can we say extraneous height increase? Didn't running boards go away in the 30's?

My 2005 2500HD 2wd short bed extended cab GMC is about the same height as five year old ford and dodge 1/2 ton trucks, and I think it is too high already but I find myself looking up when most newer trucks pull up next to me, even the 1/2 ton models. When I bought it in 2007 I asked all my friends with trucks if tonneau covers or a bed cap helped FE, but none of them ever bothered to check so they just shrugged. Absent an answer I've just been driving it as is, but since I stumbled into ecomodder.com I've found the mother lode of actual data . My overall average is 18.2 mpg over 95,000 miles; best tanks on the hwy are about 24 mpg running 55-60 mph (Duramax diesel and Allison 5 speed auto), which is pretty good for a pickup but now I know I can do better without sacrificing the performance that I care about (towing capacity if I ever buy that trailer, ride quality, comfort). For fun I just put together a 44% tonneau cover and got it on today. I'm so excited ; I've always been a hotrodder making plenty of mods for power with my cars but have left the truck stock when all my friends were loading up on exhausts, power programmers, transmission rebuilds, etc. I don't have any instrumentation more accurate than the dash display so I plan to just drive normally and let the logbook show the effect over a few tanks. Next I think I will lower it about and inch in front, since that is easy by just adjusting the torsion bars, and maybe 2" in the rear, now that I know it will help FE. I think this is going to be fun.

Oh, the other thing the Avalanche's have is a short cab extension about one foot long that goes up from the bed side, across the roof, and back down the other side and is about 2" thick, with no back. It is angled downward maybe an inch across the top, like the first foot of the "template".

[cRiPpLe_rOoStEr]

Originally Posted by aardvarcus

In addition to the factory cover, don’t forget the Avalanche also has a seamless cab to bed transition and I believe it has higher bedsides, but that could just be an illusion.

It does look higher, but it's just due to the stock hard tonneau.

[Smurf]

Get an Ultra-Gauge. Much faster information about driving technique, mod effectiveness, vehicle health, etc.