Investigation needed in GM Truck MPG

mookdoc6 · August 8, 2016

Hot/Cold effects all engines negatively and deduct efficiency from both extremes...Altitude,Wind Direction, Tires, EXTRA HEAVY WIFE? I mean there must be 1,000 variables.....

towdog333 · August 10, 2016

Me and my wife have houses in Pa and Tn , in Pa where I live the burbs with constant stop n go my truck gets around 10 to 11 mpg, in Tn with more open roads and a lot less stop and go I get 18 to 20 mpg's

Robinson99 · August 10, 2016

Not many miles as of yet to go on but all miles are country back roads, very little highway. 19 mpg with a 2" level is pretty good to me. Just hoping when I get new tires it doesn't fall of to bad.

Sent from my XT1254 using Tapatalk

Whitedog59 · August 10, 2016

My 2016 1500 Crew Cab LT 5.3 3.42 has averaged 17mpg for the 1300 miles I've driven so far. That is about 95% city short stop and go trips. I rarely can get it up to hwy cruising speed. The one 65 mile interstate run I've had showed 25mpg on the 50 mile average.

Chevor · August 10, 2016

Im getting 17 mpg with my 2013 dually flatbed travel 70mph down the highway all day. The truck weighs over 10,000 pounds.

silveradosid · August 11, 2016

tuck came with 17 inch tires on it an 308s, drive 25 miles one way to work and was avg 24 mpg. i bought a set of chevy 18 inch take offs with fuel max tires and now only get 21 mpg.

dorkweed · August 11, 2016

tuck came with 17 inch tires on it an 308s, drive 25 miles one way to work and was avg 24 mpg. i bought a set of chevy 18 inch take offs with fuel max tires and now only get 21 mpg.

And what did you learn from this????!!!

silveradosid · August 11, 2016

i learned that my speedometer is now correct with a gps, where as before i was always going faster than i really was.

SouthernSilveradoGuy85 · August 12, 2016

tuck came with 17 inch tires on it an 308s, drive 25 miles one way to work and was avg 24 mpg. i bought a set of chevy 18 inch take offs with fuel max tires and now only get 21 mpg.

And what did you learn from this????!!!

i learned that my speedometer is now correct with a gps, where as before i was always going faster than i really was.

From what I've read on here, GM actually calibrates the speedo with the 18 inch rims with the 265/65R18 tires. So any other rim or tire size from the factory will be off slightly. Another reason I'm glad mine has the 18s lol.

redwngr · August 12, 2016

From what I've read on here, GM actually calibrates the speedo with the 18 inch rims with the 265/65R18 tires. So any other rim or tire size from the factory will be off slightly. Another reason I'm glad mine has the 18s lol.

The larger rim size tires have shorter sidewalls, so the rev/mile are very close for all the tires GM uses -- which is why they don't offer the ability for the dealers to change the speedo/odo calibration.

silveradosid · August 12, 2016

that maybe true for 18 and 20 inch wheels, but the 18's I put on make the 17's look they belong on a car

ToesonTheNose · August 12, 2016

2 years 28K miles later and lifetime avg is 19.9 mpg

TJay74 · August 15, 2016

GM uses the exact same "rev's per mile" for all of the tire/wheel size options for the trucks. I have done the math on them and they are all with in .20" of an inch in overall tire height. I am guessing the poster lost mileage due to the new wheel and tire combo weighing more and or having more rolling resistance.

Sean Demura · August 17, 2016

15k on my 4.3L with a lifetime average of 17.9 mpg, mostly city driving. I'm not exactly light on the pedal either.

Also just managed 25.9mpg on a freeway run the other day.

johne · August 24, 2016

Have had one of my trip meters running for almost 30k miles. Currently 13.6 average. Maybe 70 percent highway miles. Just slightly disappointed with mpg. 14 5.3 4x4.