Is 5.3 fuel mileage really this bad?

[Samthebam]

My 2019 Custom T1 5.3 NXT (max trailering) 4x4 with a 6 speed and 3.73 gears on factory 20” wheels will get me from 18.5 to 19.2 on a typical tank of gas, but it drops to about 13-14 or so if I’m towing my equipment trailer with a Kubota tractor on board.

 

I’ve been pleased overall with my gas mileage.

[asilverblazer]

I think it is mostly the short commute. Is the truck even getting up to temp? I bet its running open loop the whole time.

Edited January 18, 2022 by asilverblazer

[dgstarr63]

I have a 2021 Silverado LT Z71, 5.3, 8 sp, 3.23 axle 4wd. I have 7800 miles.  I get 11-15 mpg in town and 21-23 highway.

[swathdiver]

Those 12.5 inch wide tires are killing you.  My daughter's lifted Sierra with 35 x 12.5s gets about 10 mpgs around town, if the tires were not as wide it would be better.  Would be better if she slowed down too!

 

Why not do a compression test?  Make sure the motor is healthy, inspect the plugs too.  I have a Tech-2 for the fleet so we can keep tabs on everything going on inside the computers and motors and transmissions, etc.

[lebag335]

'20 AT4, stock with 20" factory wheels.  14 to 14.5 on winter gas.  15 to 15.5 on summer gas.  90% short trips, city driving. 

[swathdiver]

A few years ago a guy joined a forum and said his 6.2 RST Tahoe was getting terrible mileage.  He hadn't even gone through the first tank of gas yet!  He was getting 7-9 mpg.  After some questioning it turned out he lived in a big city, downtown and had a short commute, so he was basically idling everywhere.

 

I mentioned taking it on a little trip out of town for lunch and back, and he did, the mileage was just fine.  He got about 20 mpg on that trip.

[TxTruckMan]

I bet it's a combination of the short trip, AT tires, and poor aerodynamics of the AT4.

 

I've studied tires and their affect on MPG for quite a while.  Weight plays a factor, but it's not a huge factor.  Rolling resistance and aerodynamics are the largest contributors.

 

On my 2015 6.2L Denali I ran 22" Bridgestone Alenzas (street tires) 2/3 of the year.  That combo weighed in at something like 88-90 pounds per tire.  I easily got 21/22 mpg on the highway and 16/17 overall average.  I'm a spirited driver.

 

In the winter and when going camping I also had a pair of GMC 18" All-Terrain wheels with Goodyear Duratracs that I'd flip on.  Stock sizes.  Each tire weighed in at a much lower 60 pounds or so.  I would always drop 1-2 MPG with the lighter, off-road tire setup.  Much lighter, but the aggressive tread pattern hurt my MPG somewhat.

 

Now I have a 2021 6.2L AT4 with stock 20" Goodyear Wrangler TrailRunner tires.  I don't know the weight, I assume it's in the 60 pound range, but I know that my mileage sucks balls.  I struggle to get 17/18 mpg on the highway and 14/15 in mixed driving.  It's got to be a combination of the factory lift, aerodynamics, and non-highway tire.

 

Summary - my heaviest tire got the best mileage because it had the best aerodynamics and lowest rolling resistance.

[Gangly]

On 1/17/2022 at 8:54 PM, Byrds8 said:

A lot of different posts I have read here have said leveling it doesnt drop MPG too terribly much. However, those same post will say tires will kill your MPG. If you went from a stock 9" wide tire and went to a 12.5" tire, depending on the brand you chose, it could have added a lot of weight per tire. My Sierra SLT has stock 33's on it that are 40lbs each. There are some tires that are still stock size but weight 20lbs more each. That alone kill MPG without ever going up in size or width.

 

Plus, like rbdjr said, winter grade fuel sucks also.

Doing a 2" lift, swapping to AT4 wheels and tires, and removing my lower air dam dropped me from 20.5 on the highway down to 17.5.

[GreatWhiteMexican]

I believe, like what most of the others are saying, it is your commute that is sucking your gas. I have a 2020 Custom Trail Boss with the 5.3L and 6 speed transmission. My old job was 15 minutes away and I got on average 15MPG highway, which is close to what my sticker said. My new job is now 30 minutes away and I now get a little over 18MPG highway. 

[Kilgore Trout]

A little late to the party, just saw this thread, sorry.  The OP's mileage seems low to me.  I own a 2021 Sierra 1500 AT4 6.2L with the optional Duratracs.  I get about 13 around town (that is with almost zero highway miles).  If I get even like a quarter of them highway miles,  I can see over 16 on the averages pop up.  If I stand on it stop sign to stop sign, I can definitely get sub 10 on the average, but that is driving like I am young enough to be worrying about acne.

[mwlewis558]

My 2020 Sierra was averaging around 13-15 mpg in my area on my commute to my office. Its some uphill and downhill so I'm sure that skews the numbers a bit not being on flat ground. I travel a small territory for work and its all interstate around 60-80 miles from my house. On the highway I was averaging 20-23 mpg if it kept it around 70 mph and cruised. The best I ever got was 30.3 mpg over 75 miles through South Carolina averaging 60 mph. 

 

I recently had a leveling kit installed and went with 285/60/R20 Nitto Ridge Grapplers and my city milage has stayed around the same but my highway milage has suffered a good bit. At 70 mph I'm getting around 17-19 mpgs. 

 

Hope this helps. 

 

ETA: I should have mentioned I have a 5.3 and 10 speed. 

Edited February 14, 2022 by mwlewis558
added info

[Byrds8]

2 hours ago, mwlewis558 said:

My 2020 Sierra was averaging around 13-15 mpg in my area on my commute to my office. Its some uphill and downhill so I'm sure that skews the numbers a bit not being on flat ground. I travel a small territory for work and its all interstate around 60-80 miles from my house. On the highway I was averaging 20-23 mpg if it kept it around 70 mph and cruised. The best I ever got was 30.3 mpg over 75 miles through South Carolina averaging 60 mph. 

 

I recently had a leveling kit installed and went with 285/60/R20 Nitto Ridge Grapplers and my city milage has stayed around the same but my highway milage has suffered a good bit. At 70 mph I'm getting around 17-19 mpgs. 

 

Hope this helps. 

 

ETA: I should have mentioned I have a 5.3 and 10 speed. 

Some pretty decent MPG there. I have a 5.3 and the 8 speed. I leveled mine this past week and per the DIC, I am getting about 17MPG running the highway at 75. This is without the heavy Nitto tires you put on yours. Sad too in the fact I have the muffler removed and the Air Raid MIT installed as well.

[dieselfan1]

 

I always was under the impression the T1s , although lighter than a comparable K2 , got worse mileage due to the aerodynamics. 

Yay or nay?

[newdude]

17 minutes ago, dieselfan1 said:

 

I always was under the impression the T1s , although lighter than a comparable K2 , got worse mileage due to the aerodynamics. 

Yay or nay?

 

 

Yes and no?  T1s are a good bit larger than K2.  Higher cab height, hood height, a bit wider as well.  Bigger vehicle pushing through the same air.  I think K2 airdam sat a little lower as well in the front.

 

You've also got larger diameter wheel/tire options now as well (up to 33 inch tires).  More un-sprung mass to move.  

[pokismoki]

recently drove to Canada from the California, my highway mpg was 22-24 , usually my city mpg is 14-15, here in Canada the cheap fuel is yielding 10 mpg and cost over $6/gal