GM mods the Sierra hybrid pickup: aerodynamic tweaks + LRR
 

From the Winding Road:

In addition to the hybrid system, GM added LRR tires plus a few aero mods - things that could be on non-hybrid models too...


Hmm - a deeper air dam. Remember what Ford did to it's '08 Superduty pickups?

Ecomodder - New: Ford mods their Super Duty pickups ... chin spoiler + final drive changes

I'm so unimpressed about GM and Ford chin spoilers.

My 2000 F-350 had a chin spoiler with 7.5 inches clearance - the least that will go over a parking curb.

As long as the spoiler covers the ugliest parts of the air flow (lowest hanging parts) it's theoretically 'good' ain't it?
After that point aren't you just increasing your frontal area?

You'd think so, but I recently saw a GMC pickup from the side and the stock air dam was quite a bit lower than the lowest underbody components. At the time I wished I'd had my camera - I would have like to post it.

I'm inclined to think the GM aero people found it was worthwhile to extend it down as far as they did.

I believe the Nascar philosophy is the area under the car is so turbulent, it's better to keep all air out of there.
For some racing vehicles this includes the radiator exhaust as well.
Add the grain of salt to the above, they are also interested in down-force not just cd.
Trucks also have that big rear axle to drag through any air down there. Less air underneath = less to plow the differential through.

Sorry for plowing up this old thread but I have something kind of important to add.

I found that standard chevy pickups and SUVs do not use the same power steering pump as the hybrid versions.
Look them up on ebay, quite a few of them say (non-hybrid) or hybrid and I am being told the "hybrid" power steering pumps on these late 2000s GM vehicles is in fact clutched.
Only problem is the sellers use a genaric picture so I cant just view the item and tell.
And on top of that, most power steering pumps dont come with a pully so you have to reuse the old one.