2004 GTP Bad Gas Mileage

[kapp0]

I know this question gets asked a lot, but here it goes. When everyon talks about gas mileage in here they never mention if they are getting the reading from the onboard readout or if they are calculating themselves. I have an 04 GTP and the computer is showing 16.3 average. My wife drives the car 90% of the time so it isn't getting driven hard at all. Why would it be so low? I've read through as many mileage posts on this board as I could find, but haven't come up with a solid answer.

[Burtnette]

Can't help you much but I'll try to get some information so others can help you easier. How many miles are on the car and have you modded it at all?

[JonJon68]

Try re-setting it if you can. I always reset mine especially on the highway. In Winter I get about 28-30 mpg at 70 mph and a little more in Summer.

[kapp0]

Sorry, here is more info. It has 52,000 miles. I just got it about 4 months ago. It got the throttle body replaced about three months ago, I hoped that would fix the bad mileage.

How do you reset the mileage calculator?

[Burtnette]

Originally Posted by kapp0

Sorry, here is more info. It has 52,000 miles. I just got it about 4 months ago. It got the throttle body replaced about three months ago, I hoped that would fix the bad mileage.

How do you reset the mileage calculator?

If your talking about the one in the DIC then all you have to do is push & hold the reset button on the left while in the mpg mode and it will reset.

[phewop118]

Hmmm. I think it may help mileage if it is driven so that during acceleration, some boost is used. When cruising, keep the foot as far off the accelerator as possible or use cruise control. So, give it more gas to get up to speed quicker and then stay the hell off the gas pedal. Seems to work for me. On 100 mile trip in my 07 GT I averaged 28mpg, about 60% highway. On everyday use, the car gets about 22mpg, which includes a lot of rush hour driving.

[kapp0]

22mpg is where I would like to be with it. I reset the mileage average. I will try to remember to check back later with the results. If anyone has more advice, I'll definitly try it.

I have to say that this car does make it really difficult to stay off the gas.

[phewop118]

What brand and octane of fuel do you use? I would recommend using only BP or Shell 93+ octane.

[kapp0]

Those are the two stations we rotate between. The car seems to really like the Shell gas. I have given up the gas mileage fight until this cold weather breaks. The car spends too much time warming up to get a fair result. These below zero wind chills are murder on the mileage.

[Burtnette]

Originally Posted by kapp0

Those are the two stations we rotate between. The car seems to really like the Shell gas. I have given up the gas mileage fight until this cold weather breaks. The car spends too much time warming up to get a fair result. These below zero wind chills are murder on the mileage.

Same here... and I'm averaging about 15 right now driving the best I can

[tblake]

Dummy question.... Are your guys' tires inflated corectly? How about overdrive? I realize it will take longer to go into overdrive when its -40 windchill, but does it go into overdrive? Im in MN when the highs for the past couple of weeks have been 0-5 degrees. I average roughly 17.5 to 18mpg with warm up time.

[kapp0]

I've been checking mine once a week and keeping them at 30 pounds cold/32 pounds warm per the instructions on the inside of the trunk.

[Burtnette]

Originally Posted by tblake

Dummy question.... Are your guys' tires inflated corectly? How about overdrive? I realize it will take longer to go into overdrive when its -40 windchill, but does it go into overdrive? Im in MN when the highs for the past couple of weeks have been 0-5 degrees. I average roughly 17.5 to 18mpg with warm up time.

Yes, I have to fill my front left one up about once every 2 weeks and the others hold the air pretty well. I'm not going to mess with getting new tires though since I have different ones for the summer which will hold the air 10x better which I'm hoping will improve my gas milage a decent amount. And wait how does overdrive work on the Grand Prix? On my old car (95 Dodge Stealth) there was a button to turn overdrive on or off and I don't see one on the Grand Prix.

[bricker82]

Originally Posted by kapp0

I've been checking mine once a week and keeping them at 30 pounds cold/32 pounds warm per the instructions on the inside of the trunk.

That's cool but if they're not stock tires, check the manufacturer recommendations too. I run mine at 35 PSI hot, and I say hot, cuz it gets hot in AZ, lol. Still it shouldn't make that much of a difference.

[je2345]

i drive a 99 GT and it has about 95,000 mi on it, and i only get about 13-15 mpg. It sux..i reset my odometer every time i fill up and my last reading was 225 miles to a full tank of gas. That is Garbage, and my tires are farely new Pirelli's with Nitrogen in em!! I take good care of it and give it what it needs...full synthetic Mobile1 oil changes every 5 months or so and just got the Tranny rebuilt! New Ceramic Brakes and everything!!!! I also use Fuel injection cleaner prolly 3 times every 2 months here and there. FU** DOMESTIC CARS...cant wait til my wife buys her 08 Honda CRV, so we can drive that and save me money on gas!! if ne1 has any ideas on how to solve my terrible gas problem, then let me know please!