this 5.3 engine i have been driving around lately in this 2wd '05 Avalanche is getting 16.2 mpg, according to the dash readout, and it's been driven pretty lightly on the gas pedal due to the rising gas prices. Not sure what gears are in it.
My '89 Suburban, TBI350/700r4 lifted 4" on 35x12.5 tires, 4.11 gears gets about 12-13mpg on the highway, maybe a touch better depending on weather, wind and terrain conditions, but when it was stock, with 31x10.5 tires and 3.42 gears, it was doing around 14,,maybe close to 16mpg on the freeway, again, depending on weather, wind road terrain.
I used to drive it from Phoenix to San Diego alot back when it was stock, and it didn't do too awfull bad for a bigger truck, but there was a significant difference in fuel mileage as soon as the lift went on, and also when the final bigger tires went on.,,,also, it almost seems to get better fuel mileage driving around town now over freeway driving, possibly having something to do with dragging the big brick through all that wind and whatnot..
