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Pontiac Grand Prix: Real World MPG



  • I need desperate help!!! 12.2MPG (yea some people think they got it bad with (20MPG) It was at 11.0 MPG before everything I'ved replaced, heres the list.
    1.Rebuilt SuperCharger
    2.ACDelco SparkPlugs
    3.Wire Set (spark plug)
    4.oil change every 3K (oil filter too)
    5.New PCV Valve
    6.New O2 sensor (before catylic)
    7.New Fuel Filter
    8.K&N filter and intake

    Anyone out that can really help. with any Idea Please EMAIL ME at [email protected] as you can see there has been alot of money invested and im not seeing any progress. 12.2mpg city / and 12.5mpg hwy. HELP!!! HELP!!! HELP!!!
  • well i've read that the GTP has an 18gal. tank. I reset the gallons used every time, but when I use it and the needle get down to like an 1/8th. it says i'ved only used 12-13 gallons. I reset the tripometer and from a full full tank I get 180-200 miles and the needle is low again like an 1/8th. does it sound weird or wat....
  • We have a 99 GTP that gets (according to the calculator built in) an avg of 21 mph (probably 80% city driving so far.) Then again, I can get it down to about 14 if I get on the supercharger...
  • Just turned 104K and I rarely get under 28mpg w/ highs up to 31mpg. Fantastic drivetrain and looking forward to 200K!
  • My 1999 Grand Prix GT only gets about 19 to 20 MPG with regular driving on highway and city. I heard this is normal. On my trip though on the highway only I was averaging 25 MPG.
  • mygxpmygxp Posts: 2
    it's called wind resistance. anything over 60/65 you are just pissing your gass money away
  • gearrgearr Posts: 21
    I have a 06 GT 3800 supercharge and I drive a lot of back roads
    and I am getting 25 to 28 a GAL.
    Gearr :)
  • cnwcnw Posts: 105
    I've got a 2007 GP GT, 7000 miles. When it was "brand new, fresh from dealer" and less than 2000 miles, we had one tank of gas--Albuquerque to Farmington--that we got 32+, hand calculated--not DIC readout. Average speed was 65 mph. We continue to get excellent mileage when out on open roads.
  • wikiwiki Posts: 3
    I've noticed the weirdest thing. I've had my 2007 GP for 6 mos now and drive ~ 42 mi total to and from work everyday (30hwy/70city) and was getting about 20.8 mpg (hand calculated) and I recently did my oil change and also bought a mountain bike. Since I live in an apartment, it's not very convenient for me to bring it inside, so I decided to just leave it in the trunk (w/ the back seat down, it fits very well, just have to be careful when pulling it out not to scratch the paint or damage any of the inside trunk wiring). Ever since I've had the bike in the trunk, my mileage is about 23 mpg same driving patterns, weird, isn't it? We're told that to help fuel economy we're supposed to remove any unecessary loads from the car, but in this case what gives? If anybody has an explanation for this, please let me know. It's not a rwd, so the added weight on the rear wheels is just an added dead weight (imho) I'd think. Or maybe it just evens the weight between the front and rear wheels and that makes it easier on the powertrain?
  • I just bought a 2002 Pontiac Grand Prix GT and I'm a little concerned with the gas mileage. When I bought the car, the average mpg gallon displayed was at 20.8, a pretty low number but something I was willing to deal with. I wanted to see for myself the gas mileage I was getting so I reset it. After about 100 miles of driving the average was around 15 or 16 mpg. Sure most of my miles were city, but i dont think it should be that low. I had a problem with the car a week after i bought it. when i accelerated the car would somewhat pop and jerk and would stop accelerating for that split second. I brought it to the shop and they claimed they couldnt find anything wrong with it. So I continued driving it. I reset my mpg meter again and over the next week i averaged 19.4 mpg.Then the SES light came on. I brought it to the shop, they scanned it and a code showing a problem with the MAF sensor came up. They cleaned it out, saying it was clogged, and gave the car back to me. The mechanic also said that the clogged MAF sensor could have been causing the previous problem I had. Now that I have the car back, I am averaging 15 mpg. wtf is up?
  • Don't feel bad! I have a 2000 prix, just changed the MAF sensor and still getting [non-permissible content removed] gas mpg. The check engine light went out, but no improvement on gas. If you find something out let me know.
  • 2000 Grand Prix 3.8, I just changed the MAF sensor, check engine light went off, it also seems to run better but no change in MPG. If anyone can tell me what to do that would be great. Thanks! Jason
  • I get 12 mpg and cant find out a fix.i have done a lot of this and that and still no improvement.need a fix
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