I have a 2022 High Country LM2 3.73 Duramax standard bed.

My best best DIC reading is 45 mpg over 25 miles. Thats following a flatbed on a semi with a 5 mph tailwind at 57 mph on autocruise on flat ground. The DIC says 27-28 mpg going 73 on the expressway. In my very few fillups, the DIC has read lower than calculated by about 0.75 mpg. So my conclusion, is that the 3.73 makes little difference in mpg below 75 mph. Perhaps at 80 mph things would change.

 

What do your 'tankful' mpg numbers look like?

My truck suggests that 'drafting', cruise speed and 'best 25' numbers are misleading.

 

Good info. d_todd-phelps. Hey, to you have the 3.73's or 3.23's?

Thank you.

 

I have the 3.73 which comes with the max tow package.

 

Thanx d_todd_phelps. I thought the "Diesel Off Road Package" was the only way to 3.73 gears, and the "Max Towing" only added 3.73's to the gas engines.

Thanx for sharing.

 

One of the changes on the refreshed trucks (2022.5's) is that NHT (max tow) is available on 3.0.

There are limitations on which trims, and on other options.
Not available with z71.
Not available with factory lift.
Not available with ARC (adaptive ride control)
There may be others..

'Diesel off-road' is still available:
Diesel Off-Road Package, includes (GT4) 3.73 axle ratio, (R3O) LT275/65R18C MT Goodyear Wrangler DuraTrac blackwall tires, (BVT) Chrome assist steps and (VOZ) Hard-folding tonneau cover, LPO

NHT Not available with (TRE) stock order types. Available for (SRE) sold order types only.
3.42's with 5.3 and 6.2; 3.73 with 3.0
Not available with 22's

 

Thanx redwngr. Good information.

 

Hey d_todd_phelps, what tires do you have and are you leveled?
Thank you!!!

 

Hey d_todd_phelps, what tires do you have and are you leveled?
Thank you!!!

I have a stock 2022 High Country. Not leveled, and has 275/60R20 bridgestone dueler a/t rh-s. The wheel/tire combo weighs in at 80lbs. Been running around 38 PSI. I do not have a sunroof. I do have a hard tonneau cover.

 

Thank you Todd!!

 

Its hard to do tankful numbers, because I tow every tankful. During break in, I got 24.9 calculated mpg with no towing. But that is varying speed and rpms.

Current tank all from DIC, 488 miles, 27.8 mpg, 52.8 mph. 45 miles towing an unloaded enclosed trailer. I'll fill up tomorrow and update this post w/ calculated numbers.

 

That is pretty sweet for including 3.73's and also 45 miles w/a trailer.

 

My calculated was 28.1 over 581 miles. Trailer was about 3000 lbs.

 

Whoa, and 80 pounds on the wheel/tire combo. Nice.