abausewein

Sounds like a ripper to me kinda jealous not gonna lie, my truck is stock minus an add a leaf in the rear spring packs

huanab

I have a 16 plat 5.0 with the 6 speed. Average 11-13mpg in town. and anywhere from 14 to 17 mpg hwy. (based on my last 3 trips). Truck is all stock except for 33" tires.

slow3v

Probably about 1-1.5MPG overall, but the biggest change is acceleration. 10 speed trucks are pretty ****ing fast out of the box for 1/2 ton pickups. Add in that benefit with the MPG gain and it's a win/win.

Bluegrass

There are some things to consider trying to compare years, engines and transmissions.
6 speed trans are 4 speed with 2 OD gears 5 & 6.
The 6 speed has different trans gear ratios.
The 6 speed trucks 5L are not 12 to 1 compression like 2018 and later trucks.
Then there are different rear end ratios to add to the mix for all of them.
.
10 speed are geared a bit lower overall, have 7 speeds and 3 OD gears 8, 9 &10.
Pretty difficult to have a valid compare with these differences other than expect the 2018 and later 10 speed to do better in fuel mileage when driven sanely.
It's the point with each year to add better outcomes on the average for the consumer and company sales against the competition..