Ok first off, I have a 04 QC 4.7. I have installed an cold air intake, flowmaster american thunder exhaust, and tonneau cover. I was getting around town 13.2 mpg before mods. Now I get 13.8-14mpg and this is trying my hardest to get good mpg. I try staying @ 2000rpm or lower. I talked with a friend today who only has an tonneau cover on his 04 QC 4.7. He gets 16mpg around town and has a lead foot. Whats the deal. My uncle has same truck he says he gets 12mpg around town and only got 15mpg on highway. Why the big difference between same year, engine, and cab truck. Also my other uncle has a 04 modded vette pushing 600+ hp and he gets 24mpg crusing around town. I know its a car but come on they have to be able to make these gasaholic trucks get better mpg.

 

The answer could be as simple as driving habits and where you drive. Does your friend not make many stops when he drives with little or no idling? Do you allow the truck to warm in the morning vs. getting in and going? It's tough to do an exact comparision on the mileage. Now if you're really curious, ask your uncle to borrow his truck and run a tank full through his and see how the mileage is. You will have a much better picture then.

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Brand of gas, your state and what octane rating you sue also matters.

 

im avgeraging 14.5 right now with my 4.7 around town and highway with my intake and exhaust. and i have a heavy foot cuz i love to hear my duals. id like to know what brand of gas ur friend buys that he gets 16mpg....grrr...lucky bastard. also, intake doesnt always improve your mileage, the increased air flow guaruntees more power bc theres more air to burn more fuel. so if ur goin for better mpg u might wanna go back to your stock intake or somethin a little more restrictive like volants intake.

 

I have a 4.7 qc with an auto and 17s. I have a flowmaster cat back and a air raid cai. I get no better than 11.5 mpg around town and i barely ever get on it. I think i have the 3.55 rear and i think this is the problem. I have read a few threads in here and i think i will be getting new rear gears soon maybe 4.10.

 

how many miles do y'all have on your trucks? i have an 03 qc with the 5.7l and have almost 45000 miles on it. when i first got it i got 20 mpg now i get about 16.5. my friend told me to check the inline fuel filter. does anyone know anything about that?

 

20mpg with the 5.7?!?!?!?!? wtf....ive never broken 15 with my 4.7...ive got 51k on it

 

my truck is an 03 qc with 17's. the only thing that i put on it was flowmaster. i was also using mid-grade fuel before it went up in tx.

 

ive heard alot of hype about that and read that it really doesnt help out your engine much if it doesnt need that high grade of a fuel. cant believe you got your truck to 20mpg...id be ecstatic about 16mpg. if you got 20mpg with midgrade dont you think it would be worth your money to keep buying it with little cost difference between that and the lower grade?

 

i was just checking out what it would do if i ran the cheap stuff. my gas mileage dropped after my 30000 mile service. i haven't been able to find the problem yet.