nbubak

my 98 grand prix gt only gets about 19-20 mpg.....everybody that talk that has a gt say they get about 27-28 mpg what could be the problem with mine??

BNaylor

Is that mileage in city? The higher mpg most GP owners claim is highway mpg. 19-20 if city sounds fairly normal. When was the last tune up?

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'08 Pontiac Grand Prix GXP (Dark Slate Metallic) - LS4 5.3L V8
'08 Pontiac Grand Prix GXP (Liquid Silver Metallic) - LS4 5.3L V8
'02 Oldsmobile Alero GL2 - LA1 3400 V6
'99 Buick Regal LS - L36 Series II 3800 V6
'03 Honda CR250R MX - 2 Stroke 250cc
'97 Pontiac Grand Prix GTP - L67 Series II 3800 V6 Supercharged
Timeslip 08/12/06

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GaryFenza

hey, thats normal for me for city/highway average about 19-21 mgp and i have a 3.1 SE V6.

slammedGP

There are many things that can cause bad fuel mileage. I assume you are taking those numbers from the DIC? Try resetting the DIC after each fill up, it will show a more accurate reading that way, and is usually a better number. Fluctuations in driving speed between highway and city driving, idling, and WOT runs happen too quickly for the DIC to keep up with, so it ends up showing a bad number. Next time you kow you're heading on a long highway trip, reset the DIC and see what numbers you get. Do the same when you know you are going to be doing a lot of city driving. You should see much better numbers.

A properly tuned car will also help fuel mileage. When was your last tune up? Fresh air filter, fuel filter, injector flush, and plugs and wires usually helps greatly. Low tire pressure will also lower your mpg by a large factor, as will a car that is out of alignment.

Mods that free up flow will also help with fuel mileage. When i did my exhaust work, like the PEM's, u-bend delete and muffler delete, and made a custom CAI, i saw a big improvement in fuel mileage.

HTH.