Horrible Gas Mileage! I need help!

Blak05GT · Jan 17, 2008

I have a pretty serious gas mileage problem. I have an '05 GT with the usual light bolt-ons. I tested my gas mileage and it's somewhere between 10-15 mpg depending on how much highway driving I do. The air filter is fine, the car has only 9000 miles on it and drives perfectly. I am a college student and can't afford to keep filling this thing up every 200 miles or less! Any help would be greatly appreciated.

DarkFireGT · Jan 17, 2008

Wow, that's really bad. I would clean your throttle body. Maybe try changing gas stations, you may be getting some gas that has water in it. Also check your fuel filter and spark plugs. See if that helps.

Blak05GT · Jan 17, 2008

Thanks for that advice. The gas isn't the issue as I've filled up at more than a handful of different gas stations and I always put 91 octane in it. I'll check those other things.

traded5.0 · Jan 17, 2008

Dude, that car is too fresh to be having any problems. Only 9000 miles on an '05? I wish. I have almost 40000 on mine. I guess anything could happen though. Are you sure its not a problem with your foot? I get about 15 MPG on my '05 stick but its totally my fault. Damn size 13 Filas...

FFR snakeman · Jan 18, 2008

ditto what traded said try easeing up on the go pedle

ranger04 · Jan 18, 2008

Also switch to all synthetic fluids in the engine, tranny and rear diff. That is bad mpg, my GT isn't even broke in yet and I get 22 mpg around home and 25 on a trip. Have you swapped on taller tires or wheels? If so, if you don't get the speedo corrected your figures won't be correct.

white07gt-cs · Jan 18, 2008

I know this is pretty basic but, the first thing I'd look for is a fuel leak being you say it smells rich. I get 25 at 65 and 23 at 80, both on the flat and on cruise control.

SlideWRX · Jan 18, 2008

Check tire pressures, amke sure they are over 30 psi.

How far re your trips? if you are only running a couple miles at each start, the engine is running a little rich to heat up the cat.

try starting in 2nd for a tank.

Tom

ski · Jan 18, 2008

Also, if you're driving mostly short trips like SlideWRX mentioned, and you go from light to light in city traffic in cold weather, then 10-15 mpg is about all you'll get. FWIW, my mother's Focus gets only 20 mpg around town in the winter, but she normally travels only a mile or 2 each way.
But if you're getting only 15 mpg max during long highway trips, then something is definitely amiss.

ruffy · Jan 18, 2008

Exactly what you mean by light bolt on? What I'm getting at is this, before I bought my CAI and tune I tanked up with Super Plus @ 93 octane and the car ran like crap, although I didn't measure the gas mileage I'm sure it was horrible. When that was done I went back to normal unleaded @ 87 octane and the car ran fine. Perhaps your (and this is only a guess) you are running too much octane if you don't have a tune.

302stang.93 · Jan 18, 2008

You an fill up at night when it is colder to get more gas for your money, because gas gets denser as it gets colder so if you wait till night you get more gas per dollar paid.

stanmckinney · Jan 18, 2008

A lot of my driving is in town. It's about 4 miles to work and 4 miles back. That with a stop or two at Wal-Mart usually gives me 13.4 miles per gallon. I can't get any better no matter how hard I try.
On the road I have gotten as much as 28 miles per gallon.

o0Dan0o · Jan 18, 2008

302stang.93 said:
You an fill up at night when it is colder to get more gas for your money, because gas gets denser as it gets colder so if you wait till night you get more gas per dollar paid.

LOL man, thats such a small difference, seriously, it's basically none.

chad9350 · Jan 19, 2008

Get a good dyno tune...

I get about 18mpg city and 28mpg (80mph) cruzn' I-10 with 4.10's on an efficient tune... A race or torque tune will yeild less mpg.

The money spent on a good tune at a reputable dyno will save you that much $$ and more in a years time in gas.. AND get the best performance out of YOUR specific car.

Just my 2c

Best of luck with MOOOOtang and school.

claytucc3 · Jan 19, 2008

I drive the piss out of my car and I get no lower than 17-18 mpg. Did you change rear drive gears by chance?

Come to think of it...my wife had an 06 VW Beetle Convertible that got 12 to 13 mpg and the dealer was never able to figure out why. We traded it in for a new one, of the same exact model and motor size and it got 24 mpg. We did every thing possible to the car from changing the fuel tank to the injectors. We were never able to figure it out. So, the dealer took it back. I am not a firm believer of VW, Audi or Porsche anyway. But, her dad works for Audi so we can't beat the deals.

Blak05GT · Jan 20, 2008

Thanks for everyone's input. I'm thinking about getting a quick check-up at a shop to make sure there are no clogs anywhere in the system or something like that. I'm also considering a tuner like the SCT Xcalibator or DiabloSport Predator. Anyone think those might help? Now to answer a few people's questions.....light bolt-ons are an MMR CAI, JBA headers, and a B&B exhaust. The car is also lowered an inch and has 18's in the front with 19's in the rear. The tire pressure is fine and I don't have a heavy foot. I get on it once in a while but even on the highway when I'm cruising at 70-80 in 5th gear the gauge goes down like crazy.

DarkFireGT · Jan 20, 2008

With tune and cai I picked up about 3-5MPG in the city and 4-6MPG on the highway. A good tune is definitely worth it. That is, if you can keep your foot out of it

white07gt-cs · Jan 20, 2008

DarkFireGT said:
With tune and cai I picked up about 3-5MPG in the city and 4-6MPG on the highway. A good tune is definitely worth it. That is, if you can keep your foot out of it

What tune do you have??? My tune add zoot to the car but gas mileage is down about 1 mpg AND I now have to run 91 octane.

DarkFireGT · Jan 20, 2008

93 race from Brenspeed. Also running the C&L Racer intake. I generally drive pretty conservatively on the street.

homebrewer · Jan 20, 2008

I'm surprised that nobody else has mentioned this, but if you do not have a tune in the car to run 91 octane (which it sounds like you don't) this is your problem....

Higher octane fuel burns slower than a lower octane. A higher octane fuel such a 91 or 93 gives you the ABILITY to make more power, it doesn't make it on its own. If you're tuned correctly for it, its a great thing. If you aren't tuned, it will only hurt your performance, both power wise, and economically.

Assuming that you aren't tuned, fill up with some plain old 87 octane, and I promise your mileage will improve. I still don't understand why most of America believes that premium fuel is somehow magically "better" for your motor, no offense to you personally....

Horrible Gas Mileage! I need help!

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