- Dec 3, 2011
- 523
I never thought I'd be one posting about bad gas mileage....LOL!! Those kind of threads always kind of annoyed me. But I havent been able to find out why my mileage is suffering...
I used to get 20.5mpg on the highway on average. I only drove my truck 7000 miles last year, so I dont know exactly when it started to suffer. I remember going up north with the Envoy in July and realizing my mpg sucked but thought it was a 1 time anomaly - not so apparently. Ive been driving the truck a lot more lately and its definitely not a 1 time thing.
I replaced my oxygen sensor (original) and my city mileage went up 1.5 mpg but my highway mpg suffers the same as before though. I tuned my truck up at the 100k mark with Delco iridiums (of course!), I use synthetic 5w/30 and only get gas at the same top tier gas station (have a gas credit card that gives me a discount). I replaced my air filter AND removed my spare tire in the last months - No difference in mpg at all.
Im averaging 16.5mpg in the city and 17mpg on the highway. No CEL light, no pending codes.
Air in my tires are all at 36psi each. I have Destination A/T's. Wondering if the A/T tires are my problem? Because at this point, thats the only thing left I havent changed...lol
I used to get 20.5mpg on the highway on average. I only drove my truck 7000 miles last year, so I dont know exactly when it started to suffer. I remember going up north with the Envoy in July and realizing my mpg sucked but thought it was a 1 time anomaly - not so apparently. Ive been driving the truck a lot more lately and its definitely not a 1 time thing.

I replaced my oxygen sensor (original) and my city mileage went up 1.5 mpg but my highway mpg suffers the same as before though. I tuned my truck up at the 100k mark with Delco iridiums (of course!), I use synthetic 5w/30 and only get gas at the same top tier gas station (have a gas credit card that gives me a discount). I replaced my air filter AND removed my spare tire in the last months - No difference in mpg at all.

Air in my tires are all at 36psi each. I have Destination A/T's. Wondering if the A/T tires are my problem? Because at this point, thats the only thing left I havent changed...lol