Custom 2500 gas mileage questions

i82much · January 29, 2021

to me, it sounds like these new engines do a smidge better on gas and that may be enough to bring over some 6.0 owners or convince someone who was considering a new 1500 to go with a new gas HD.

GMC4Zee · February 17, 2021

Well I was getting about 7 MPG with my 6.0 towing the 5th wheel and from the reports people are getting 8 to 9. so if I gain 1.5 mpg on a 36 gal tank, that gets me better than 50 miles of extra range. I will take that any day. My 3500 is on order so we will see.

mrjulian416 · February 18, 2021

So I have a '21 2500 SLT CCSB. Just over 1k miles and looking at "trip 2", which was reset when I took delivery at 21 miles, it's showing 13.4 mpg. This is a mix of highway and grocery getting over those thousand miles.

My best 50 mile average is 16.9, which was mostly highway, and well behaved city.

If I look at the 20 mile average when driving around town, and launching at green lights like someone else is buying the gas, it's about 12.3.

Haven't towed yet.

Bottom line, in mixed use it's about the same as my '00 1500 SLE 5.3 ECSB. Maybe 1mpg less.

If I need to just run an errand in town, I take the '00. The 6.6 gas 2500 does not like stopping and going. If it can stay rolling it's in the 16-18 range unloaded. Cruising on flat highway at 75mph I'm seeing about 18 instantaneous mpg.

How you drive it has a huge affect. Soft on the pedal vs hammer down makes a big difference.