Well, I just got back from a road trip to Frankfort, KY and back, for a total of 1100 miles. I was rolling, usually around 80mph or better, and it was a bunch of hills thru WV, but all 4 tanks of gas yielded right around the same mileage, about 16 mpg. It's about 2mpg less than the 5.3 got, but last time I took this trip I had the 17's on instead of the 20's.

BTW, someone around here claimed to get 24.5 mpg in a 4x4 Tahoe.....that's B.S! There is no way a 4x4 Tahoe is going to get 24.5 mpg, I don't care if GOD tunes it and it's run in a wind tunnel. That just ain't gonna happen.

 

I think a lot of the variation people are seeing in mileage is due to the average speed they drive. If I cruise along at 80 I get 13-14, but if I cruise along at 50-55 I can easily get 18 (according to the mileage PID I set up in EFILive).

 

the best ive gotten was 23mpg....it was ALL freeway and ALL with the cruise set at 65mph. that was alot of mods ago too. now i average 16 mixed driving with my foot to the floorboard alot of the time.

 

You guys claiming 21+mpg will have to excuse me for being sceptical. These are 4500+ lb vehicles with the aerodynamics of a brick. There are a bunch of 4cyl. "economy cars" out there that don't get much better than that. I guess I'm just ignorant as I usually don't drive all highway and rarely baby it for the whole tank of gas. I was happy with 16 considering I was rolling pretty fast and it was a lot of up and down the mountain.

 

ive done the 23 mpg twice. i forgot to mention it was also winter time without any ac/heater running at all. windows up on factory o5 silverado wheels on the factory tires 245/75/17??? i was trying to max out my milage.

620 miles to one tank. i was suckin fumes on the way into the stations too now im happy when i get around 420 to a tank

 

Sorry to burst your bubble..........SLOW DOWN! Ever think about that?
65-70 mph will yeild great fuel economy when set on cruise.
Like I said before, I can get 21+ mpg on average in my truck with the the cruise set on 68mph, A/C on, windows up, tailgate up, full tank of fuel, and a total of three people inside.
That's with my LQ9 6.0L, ECSB, 275/55/20 tires & wheels, and 3.73 gears.
If my 6.0 can get it, I know the 4.8 & 5.3L engines are capable of it.
You drive an SUV. That could have an impact on the particular circumstances.
Then again, I still say your driving too FAST!
Mine too will net 16 or less MPG's driving at 80-85mph. So I drive slower. If you want good fuel economy, your just going to have to sacrifice some speed and start actually looking at the scenery your passing.

Jim

 

I got 17mpg running anywhere from 90-100 mph from VA to FL... I covered some ground on that trip. Tha was some smokey and the bandit type **** right there... I was actually pleased with the mileage though... even with the occasional 125 shot rolling down I-95 in the middle of the night...

 

I recently did a 750 mi round trip
about 500mi interstate, 1/2 at 76mph, 1/2 at 86mph
250mi of hills & curves at 60mph
averaged 20.6 for the whole trip.

That 2 wheeler should be better than 16!

my 3.42s don't hurt I guess

 

my mileage was on 3.42's as well... tall gears tend to help out on the highway.

 

My girlfriend can get 22mpg on my truck...I've watched her multiple times, but she drives like a grandma: 60-65mph MAX with slow takeoffs and even throttle transitions. I only get 16mpg on a good day with a tailwind because of the way I drive: 80-85mph with rapid takeoffs and rapid throttle transitions. HOW you drive makes a HUGE difference...and the difference in gas mileage between 65mph and 80mph will blow your mind (I've given up caring....I live in the desert and just want to GET THERE NOW !!)