[autoarcheologist]

I've been lurking and reading for a few days and decided to register. Not too many people trying to improve the FE of an SUV, but I'm one of them.

A little background...

We bought the Tahoe to tow our 1966 Streamline Countess 26' vintage travel trailer. Last year we towed it over 3000 miles to Northern CA, and to Yellowstone and more.

At the moment we are touring the Southwest, the Grand Canyon, Moab, Bryce Canyon, etc before hitting Disneyland and heading back north.

We are lucky enough to not use the Tahoe for commuting since we work from home, so it's mostly used for Costco runs, towing, long trips, and the occasional trip in town that's too far to walk. I'd say we drive about 10k miles per year, with almost half of that on long vacation trips.

So far on this trip we are averaging 13.3 MPG, mostly towing, which I think is pretty good. But I would love to improve it, and also love to improve just the Tahoe for when we need it for long trips.

We have a 1974 Alfa Romeo Berlina and now a 2002 Saab 9-5 2.3L that both nearly double the Tahoe mileage, so we use those whenever possible as well.

Plans for the Tahoe include:

Lowering it - partly for handling, also for FE. I already have the kit, just need to find the time!
Removing the roof bars, and switching out the Z71 rack for a sleeker rack. We still use it occasionally, so I want to keep the side bars on.
Partial grill block. I'm worried about trans temps when towing, so need to be careful with this.
2" airdam on bottom of bumper
Partial belly pan. I'm not sure I have the time for a full pan, but could do the engine relatively easily. It has skid plates, which might help a bit?

The Tahoe has the 5.3L Vortec, with the 4-speed auto, 4WD and a 3.73 rear end with tow package.

We rarely use 4WD, and frankly would ditch it, except occasionally we need it to back into a tricky camping spot. Like tonight, uphill on gravel, we wouldn't have made it without 4WD. Otherwise we run in 2WD.

I have stock sized Michelin tires, 265/70R17 on the stock Z71 wheels. When towing I run at 41 PSI, around town usually at 35 PSI.

I hope that's enough for now. I have done some driving modifications, when I was commuting to work in a Focus I was trying to get over 24 MPG on a tank, I don't remember if I ever did.

I'd love to get 20 MPG on the freeway, say on trips to San Francisco. At the moment we struggle to hit 18 MPG. Part of the trouble is keeping speeds down, on a 10 hour trip a few MPH adds up in real time saved, especially with a 2 year old in the car.

Looking forward to learning more and sharing our results!

Ian