2021 Tahoe RST Abismal mileage

[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.