2021 Tahoe RST Abismal mileage

[Gibby13]

Finally got some better gas mileage. Went back down to 87 gas, just did a trip to inlaws for nephews graduation and I got 15mpg on the highway with cruise set at 94.

 

[fasteddy]

94?
Do you live in Germany and drive on the autobahn?

 

[Gibby13]

94?
Do you live in Germany and drive on the autobahn?

Nope, I just stay under the excessive speed limit, which is 25+ here.

 

[89Suburban]

Auto means that the four-wheel-drive only engages when needed. It would make a slight difference possibly, but not a significant difference. Many people leave their vehicle in auto all the time. Not a factor overall....

Doesn't the front driveline stay engaged when in auto and the transfer case engages when needed?

 

[Stbentoak]

Doesn't the front driveline stay engaged when in auto and the transfer case engages when needed?

I think it’s actually the opposite. The front driveline only engages when wheel slip is detected. Otherwise it rides along not rotating....

 

[Thislife1977]

Does make a significant difference?

I’m now getting 16mi/gallon. Yukon isn’t a AWD vehicle, so the 4wd engages often even when you don’t need it like on bumpy roads or steep roads. Auto should be used when the road conditions change like a light snow/sleet/ice, gravel, bad storm...etc.

https://www.gmc.com/gmc-life/how-to/when-to-use-four-wheel-drive

 

[Gibby13]

Finally got some better gas mileage. Went back down to 87 gas, just did a trip to inlaws for nephews graduation and I got 15mpg on the highway with cruise set at 94.

On the way back, I set cruise at 84, averaged 16.7mpg but there was a lot more traffic going that speed and drafting definitely helped.

Also both of the above are with the vehicle in 2wd, we had been in auto for the first 4000 miles we had the vehicle.

 

[Fireman591]

Finally got some better gas mileage. Went back down to 87 gas, just did a trip to inlaws for nephews graduation and I got 15mpg on the highway with cruise set at 94.

94!!!!!! I will say I hover around 20mpg at 70-75mph. Anything over that my mpg drops into the low teens. These things are like bricks and they do not do well mpg wise when above 70.

 

[Toasty]

Couple of things - the 5.3 and 6.2 have Dynamic Fuel Management, can can run on as few as 2 cylinders. There's no visual indicator on the dash to show this like previous systems. SOME half ton pickups have been built and sold with this system disabled electronically due to the microchip shortage, with $50 credit to the buyer. (Yes, it is disclosed) but this has not been done on the Tahoe/Suburban/Yukon/XL. And as for the Auto/4WD? when in Auto, the front driveline is engaged, but a very low percentage of power. If slippage is detected, greater power is sent to the wheel. So running in Auto full time will indeed impact your mileage. could be .5-1 mpg I would guess.

 

[Kpwweb]

I think it’s actually the opposite. The front driveline only engages when wheel slip is detected. Otherwise it rides along not rotating....

No. Auto engages the front axle disconnect so everything in the front turns and “drags”. Transfer case is engaged when needed, which also includes starting from a dead stop. I will get 2-3 mpg less on auto.

 

[colinel]

Hi guys,
I bought a 21 Tahoe RST back in February. Before that I had an '18 Suburban and before that a '15 Tahoe. My wife likes a new truck every few years and drives primarily in suburbia as a school bus for our kids. Our driving habits have not changed however on this new Tahoe, we have been averaging about 8 mpg. It's advertised as 14 mpg city but were getting barely 1/2 of that. Anyone else experiencing a similar issue? We are at the pump almost weekly. It's a complete disappointment. I've had it in for servicing once under warranty already for an SRS light but they didn't note anything unusual. Any suggestions? Thanks for the help!

Demand is so high for these vehicles that you should look into trading for the DURAMAX. 30mpg in my embarrassingly large suburban at 70mph. It’s insane. You can keyword search by cylinders (6) on cars.com

Lol, this feels like an ad.

 

[Baja_Bob]

We are at about 1,500 miles and about 160 hours on the engine.

How much idling do you do? 160 hrs for only 1500 mi seems really high. My 21 has 1474 mi and only has 45.5 hrs, are you doing a lot of remote starting?

Remote starting has an effect on gas mileage.

 

[aboss3]

Just did 1,000 mile road trip on my '22 Yukon Denali XL, and we averaged about 17 on the highway and 13.9 in the city. Kept it in 2WD mode all the time, and cruising speed of 75. Hope it helps.

 

[Matt Wilson II]

Hi guys,
I bought a 21 Tahoe RST back in February. Before that I had an '18 Suburban and before that a '15 Tahoe. My wife likes a new truck every few years and drives primarily in suburbia as a school bus for our kids. Our driving habits have not changed however on this new Tahoe, we have been averaging about 8 mpg. It's advertised as 14 mpg city but were getting barely 1/2 of that. Anyone else experiencing a similar issue? We are at the pump almost weekly. It's a complete disappointment. I've had it in for servicing once under warranty already for an SRS light but they didn't note anything unusual. Any suggestions? Thanks for the help!

Kind of late to the party on this article. Sorry. I had a similar experience during break-in with my 2021 Z71. I have actually commented on a couple of posts, as well. When I swapped out the factory oil with Amsoil Signature it definitely helped. I drive 80% highway and in the beginning of my ownership I saw 13 mpg average. I'm now at 16.5. I hope this info helps. Any questions, feel free to reach out. I'm definitely new to the GM realm. I have been a Mopar guy until last year. So, there are folks here with more knowledge, but I am willing to answer any questions I can.

 

[SSGUNNER]

Just drove my RST from SoCal to Utah, about a 391 mi trip. Actually went as high as 29.3

 

[GMCnewbee]

I would check the gearing. Maybe it is not shifting all the way up to high gear? Check your RPM at 60 MPH and do the math.

On a side note, many years ago my Dad bought a huge Mercury station wagon. He swore that he could see the gas gauge drop as he was driving. On further review, there was a gas leak in the fuel line.

 

[RST Dana]

Just drove my RST from SoCal to Utah, about a 391 mi trip. Actually went as high as 29.3

50 mile average is not necessarily indicative of the true trip mileage. Most here will agree, checking mileage vs gallons used manually, is the only true test.

 

[ChemEng]

6.2 Z71 375 miles on the odo

I get ~18 on the way to work 4 miles of backroads then 11 miles of cruise control at 75mph.

I get ~14 on the way home. No idea why it is so different, but its consistent...

I am consistently getting 2 mpg average better on the second tank of gas than on the first. I am relatively certain the dealership put regular in it instead of premium for the first tank.

Lifetime average is mid 15s

(all mpg reported from the lie-o-meter)

where do you get the #hours from?

 

[RST Dana]

So…it has 375 miles and you had to refill the tank?

 

[ChemEng]

Yep, refilled when it got to 1/4 tank. I never run my cars to E. I think I put something like 17-18 gallons in it. At 15.5mpg average that's about 275 miles which sounds about right.