20mpg average possible?

[denali93314]

I can get 21mpg on the highway in a 04 Duramax Crew Cab 4x4, but only 17 in the city. My 07 Denali is no where close. To get good mileage in a big vehicle, it needs a turbo diesel.

 

[tx tahoe z71]

Used to get 14-15 city and 20 highway (going easy on the gas at 65mph) when I was stock with a Wheatley 93 tune. Before the tune, it was about 12/16. I have 4wd, A/T tires and 3.73's, so I could see someone getting 21-22 on the highway with a 2wd and 3.23s and skinnier tires, but there is no way anyone could average that.

Get a tune. That's the biggest difference maker. Other than that, change your spark plugs (I ran NGK TR55's gapped at .055"), clean your MAF and replace your front O2 sensors with OEM replacements (not Bosch or a Chinese brand).

 

[bnoland]

I just got my 2008 PPV Tahoe about 3 weeks ago. I have been runing mid grade gas and do about 70% freeway (75-85mph most of the time) driving. I am not heavy on throttle all of the time but I don't baby it ether and right now I have been getting 15-16 mpg. Last tank was 15.8. I am going to get a tuner/have it tuned and see what kind of improvement it provides.

 

[denali00]

Used to get 14-15 city and 20 highway (going easy on the gas at 65mph) when I was stock with a Wheatley 93 tune. Before the tune, it was about 12/16. I have 4wd, A/T tires and 3.73's, so I could see someone getting 21-22 on the highway with a 2wd and 3.23s and skinnier tires, but there is no way anyone could average that.

Get a tune. That's the biggest difference maker. Other than that, change your spark plugs (I ran NGK TR55's gapped at .055"), clean your MAF and replace your front O2 sensors with OEM replacements (not Bosch or a Chinese brand).

..might have been the best info ive found so far..lookin into the bb tune

 

[rabbiporkchop]

Has anyone here achieved a 20mpg average (highway/city)? Normally Im all about HP with most of my vehicles, but after trading in a 22mpg, 400hp G8 GT for our Yukon, I miss the great mileage and power combo. Im thinking of doing the following mods in pursuit of a 500 mile tank of gas:
Intake, exhaust, LT headers, 2/3 drop, Comp 401-13 VVT cam, and some tuning.
My wife commutes almost 75 miles a day, mostly on the interstate, but Texas just raised the I-35 speed limit to 75, which was awesome for the G8, not so awesome for that brick Yukon. Some aerodynamic mods would be nice, like maybe removing the roof rack, but not sure how to go about doing that..

If you have the 6.0 with the 4l80e I doubt it is possible, but the new ones with the 6 speed it should easily be possible.

 

[fiatdale]

Used to get 14-15 city and 20 highway (going easy on the gas at 65mph) when I was stock with a Wheatley 93 tune. Before the tune, it was about 12/16. I have 4wd, A/T tires and 3.73's, so I could see someone getting 21-22 on the highway with a 2wd and 3.23s and skinnier tires, but there is no way anyone could average that.

Get a tune. That's the biggest difference maker. Other than that, change your spark plugs (I ran NGK TR55's gapped at .055"), clean your MAF and replace your front O2 sensors with OEM replacements (not Bosch or a Chinese brand).

HUGE fan of the Wheatley tune. Hes done all my trucks so far. Awesome guy too.

 

[Bryansan]

factory says 12-18. I net a solid 10.5 consistantly. Ugh.

 

[tx tahoe z71]

HUGE fan of the Wheatley tune. Hes done all my trucks so far. Awesome guy too.

Best in the biz

 

[NYrr496]

When I drive my 09 Suburban from NY to Florida, I average 20.5 MPG. Coming back home, I do 19... Every time.
I'm not positive, but I suspect that southern states may not oxygenate the gas like in the NY area, so I'm getting better mileage from their fuel.

 

[Goodinblack]

I think the trick is to keep it at 1500 RPMs as much as possible.