Very Poor Gas Mileage

[swathdiver]

A lot of great responses. Thank you all very much. I appreciate it. So to answer some of the questions...

I forgot to ask, what size and brand of tires are on each truck? Are they wearing properly?

Poor tread design can cost you MPGs, a bad alignment can cost you MPGs and some tire sizes are more efficient than others.

 

[petethepug]

OEM Esky 22’s are pushing 90lb with the tire. 24’s will be more.

I can tell you the shift behavior in our past L92 Denali vs our L9H Esky ESV is not the same. The Denali felt faster even though it was rated at 385 vs 403 in the Esky.

Probably the 20” alloys on the Denali and different trans programs. If you’re looking for long term milage solution start planning to do a 6 to 10SP swap when trans rebuild time comes.

2007.5-2013 GM Truck - Powertrain Swap Solutions

www.powertrainswapsolutions.com

 

[Marky Dissod]

one would think the different weight and axles ratios, engine size, etc would make one better or worse than the other but NOPE
when I went to the 6.2l, from a 5.3l I was kinda scared I was going to get like 8, but that never happened. I mean I can make it happen but that's a workout.

@Doubeleive is not a leadfoot, he is a thorium-foot.
In your special case, better axle gearing means more fun, better transmission protection, but your MpGs are not likely to improve.
That you get the same MpGs with a 6.2L as from a 5.3L, implies that you are SLIGHTLY gentler on the 6.2L ... ?

I got two leadfoots (I brake hard, so I can gas hard ... so I can brake hard ... so I can gas hard ...).
I don't RACE, but my riders always ask if I'm in a rush. "Nah. Are YOU? Please say so, I'll turn it up s'more so you won't be late!"
If I ever get a (used) GMT900 with a 6L80, I'll STILL upgrade its axle gears from 3.08 to 3.73. MIGHT be able to tolerate 3.42 IFF it's a 6.2L.

4L60 & 6L80 suvs (& many but not quite all pickups) were undergeared in their axles by GM.