So yeah i drive a 2001 quad cab 4.7 5 speed with an aftermarket intake and a cat back magnaflow-like exhaust and i get about 15 in the city and close to 20 on the highway... that is even at an elevation of 7500 feet here in colorado. is your truck straight piped to hell? because if it is, the exhaust is moving past the airflow censor too quickly which in turn tells the computer to put more gas into the engine. i have a friend with a 4.7 durango automatic that did a 4 inch straightpipe and cant get above 12.5, no matter how nice he is to it.

 

on my last tank i got 17 mpg

 

I average about 16 combined. Last fall was getting about 18-19. hate winter gas.

 

I get 15.5 in my 3.9. city or highway doesn't seem to make any diff.
superchip tuner set to "performance"
cheap cold air intake.
tonneau cover
american racing 18" rims
i baby it 90% of the time.
no additives whatsoever, GTX highmileage motoroil 15w 30
92-94 octane gas from sunoco or shell.

 

You are wasting money on higher octane gas, the truck is made to use 87 octane and anything more is almost always just throwing money away. I did have to run 89 with about 2 gal of 92 when the spark plugs where shot so it would not knock.

 

Run some zMax in the oil. Helps the parts and probably will help millage. Best way to get better millage is to fix something wrong with your truck, I bet you have something wrong with it. Cat, intake, exhaust somewhere there. They can each cause problems.

Chris

 

I'm getting 16.5 mpg in my 3.9 club cab now that the tranny is fixed.

 

as soon as i get my brakes fixed i hope to be back up into the 16 highway range again.

 

wow 16 highway with the 4.7? i can get 20-21 on summer gas on the highway that seems a little low to me

 

+1 i too get 20+ on the highway sooo i would want to know what else is wrong w/ u truck if its not in the 18+ range (at least)on the highway