Thread: Piss Poor MPG

Any one else getting poor gas mileage lately with all this heat?
Daily temps are sitting 100-103° My ac shows 104-108°

I swear my mpg is sitting any where from 11.5 to 14. 11.5 is if im sitting in the car at a light or when remote start my car from 1/4 mile away and get out to my nice cold car.

Driving around town i try to keep shifts under 2k ill do 41 so i can use 4th gear and avg i get 14mpg.

Over all even before this heat all was really able to do was get 240 before the light came on.

I change fuel filter every other oil change pcv valve done 6 months ago.

Autolites 104s gapped at .055 not that old prob 2 months old

Well truthfully you should be getting better fuel economy in this heat. The added heat helps with fuel vaporization and up to a point it should help with fuel economy all other things being equal. I dont think I have EVER gotten that poor of fuel economy out of my GP. Even with mostly city driving I think the worse Ive ever seen out of it was 19 and that was with some spirited driving too.

I would say you have other things going on but its not heat related.

Now, you also made a statement that I hear a lot when I talk to people about fuel economy. "I swear my mpg is sitting...." or "I think I get..." or "Somewhere around..."

If you are swearing and cannot say factually, then that tells me you are guessing to some extent. If you go off and try and troubleshoot a fuel economy issue with guesstimations, you will run yourself ragged and chase your tail. You really need documentation.

I keep extensive fuel logs on my vehicles. I write down both the trip odometer and regular odometer readings on every fuel receipt then manually calculate the mileage for that tank and then keep all that in a fuel log. When I fill up, I fill that thing until it cannot take not one more drop of fuel. This way I get consistent readings. Filling it up until the handle clicks off, well you're just going to be all over the place.

The best thing for you to do is to fill that tank up until it runneth over. Then drive until you feel the need to refuel. Fill it up the same way again and then manually calculate your mileage. Then you need to do that for a few tanks. Preferably you would do it on every tank to have a running history and long term analysis of what your fuel economy is doing over the spring, summer, fall and winter months.

But after you do it for at least a couple of tanks, then let us know what you are getting for sure. But I assure you that the heat is not the reason your economy is bad, that actually helps it. Its also the reason most vehicles come from the factory with a 195* thermostat in them. It promotes fuel heating and that promotes better fuel vaporization which in turn produces a better burn and thus better economy.

i constantly get 17 or 18 mpg. on a straight highway drive going up north i only got 22. unless you seriously sit down and tune the crap out of these cars then they just dont get great mileage once you mod them. mine is untuned by the way, im running a DHP 1.5 file with a few codes deleted.

there has to be something wrong in your car for you to be only getting low teens for mileage though. o2 sensor gone? fuel filter completely shot? gas leak?

I am getting an average of 28 mpg. That is average over the past 2-3 months. On the last trip to Canada (330 miles or so), I got an average of 32.8 mpg. And if I was doing all highway, I am sure I could get 34+.

But the tune helps considerably. I was only getting 25mpg MAX (avg 20-22) before I tuned it. So the tuner has more than paid for itself.

But I also agree that the heat doesn't have anything to do with it. My car gets better fuel mileage in the heat than in the cooler temps. Days that reach 90° give better economy than ones in the 70s.

Also, I drive 100+ miles a day. I keep extensive records, much like scotty. I put everything into an excel spreadsheet, since I always have my laptop for my tuner, so mileage and trends are very easy to compute accurately.

Originally Posted by Zef_66

I am getting an average of 28 mpg. That is average over the past 2-3 months. On the last trip to Canada (330 miles or so), I got an average of 32.8 mpg. And if I was doing all highway, I am sure I could get 34+.

But the tune helps considerably. I was only getting 25mpg MAX (avg 20-22) before I tuned it. So the tuner has more than paid for itself.

But I also agree that the heat doesn't have anything to do with it. My car gets better fuel mileage in the heat than in the cooler temps. Days that reach 90° give better economy than ones in the 70s.

Also, I drive 100+ miles a day. I keep extensive records, much like scotty. I put everything into an excel spreadsheet, since I always have my laptop for my tuner, so mileage and trends are very easy to compute accurately.

WTF! I cant get past 22!!!!! >:|

I will also add, that in many cases, not necessarily all, but in many case issues with a vehicle will first show up in fuel economy. If you have a long fuel economy record in which to refer to you can spot these trends really quickly.

My GP got 28mpg all highway when I first got it. So Im surprised when people report low 20's on an all highway run. But some tweaking here and there and I was up to 33, sometimes 34 on highway runs and I have more planned once I get it all back together. I just dont see any reason for the 3800 to not get very high 20's at a minimum on all highway runs.

its all the tune.

Originally Posted by Bio248

its all the tune.

Or lack thereof.

Actually, it's alot less complicated than that... It's called ethanol.... I only buy 100% gas and it last alot longer... I get about 3-4 MPG more with 100% gas than with the mixed crap... It only costs about 10-15 cents more per gallon but you make it back after each fill up... There are only about 4 or 5 gas stations here in Tulsa that still 100% gas... Check out this write up and forum...
TulsaNow Forum - REAL GAS - NO QTrip E10

and a write up in the Tulsa World...read the comments...

http://www.tulsaworld.com/news/artic..._12_OKLAH36326

22MPG city, currently.

I seriously doubt that E10 is the source of his horrible fuel economy. Its certainly not helping, but its not making it that bad.

However, you gave me an idea too. I think I will start a thread here that tracks those stations that sell pure gas. I need to do some research though. I think we need to support these stations. I dont understand the philosophy of using a fuel thats tied to a major food source and thus drastically drive up food costs all the while getting less fuel economy that makes you stop more often to fill back up with the same fuel thats driving up food costs.

Originally Posted by SyntheticShield

I seriously doubt that E10 is the source of his horrible fuel economy. Its certainly not helping, but its not making it that bad.

However, you gave me an idea too. I think I will start a thread here that tracks those stations that sell pure gas. I need to do some research though. I think we need to support these stations. I dont understand the philosophy of using a fuel thats tied to a major food source and thus drastically drive up food costs all the while getting less fuel economy that makes you stop more often to fill back up with the same fuel thats driving up food costs.

Agreed....But i have been tracking mine and I have noticed 3-5 mpg difference in city driving... I calculated an average of 23mpg city highway mixed one week with 100% gasoline and 18mpg the next week using E10. They were identical driving conditions because it was from home to work and to lunch to work and then back home. I also calulated a difference when using 91 octane compared to 87... I know in '04 the S3 3.8 doesn't require the use of premium but I do notice a big difference when I do...

hey keet another tulsa member

Ya i only fill up at 21st and lewis at that 66

My car is getting crappy mileage as well as compared to my 97.

Both cars: L36.
00 has 65k miles on it.
97 has 118k miles on it.

00 gets 17 around town, 21 highway.
97 gets 24 around town, 32 highway.

Figure that one out...

Originally Posted by BackInBlack

My car is getting crappy mileage as well as compared to my 97.

Both cars: L36.
00 has 65k miles on it.
97 has 118k miles on it.

00 gets 17 around town, 21 highway.
97 gets 24 around town, 32 highway.

Figure that one out...

Who drives what car? I find that my wife gets crappier gas mileage no matter what car she drives because she doesn't think about how she is driving. I think about my driving and drive more cautious and thus get better fuel mileage.

I just put my car on the road today for the first time in a year. With the new build I'm sitting at about 10.2MPG on the DIC

I'm only getting 23- 25 m/g in my 04 gtp. when i first got the car a month ago i was getting 19m/g. Of course when i bought the car it had a plugged air filter and crappy fuel in it. I put in a new air filter, changed the fuel filter, changed to Royal Purple 5W30 motor oil, and run premium fuel. i removed the drivers headlight yesterday and could not believe the little openning there is for the air inlet( OMG). I did get it scoped and will post the results later this weekend, the O2 sencer (#2) is NFG and the TPS is wacked out from what the Tech told me ( what ever that means). So I'm off the the dealer next week to have them look at everything (under warrenty still, i hope).

OH YA GAS WENT DOWN HERE IN SASKATCHEWAN CANADA TO $1.33/L

Originally Posted by Quicklynx

$2.92 9/10 a gallon for premium... amazing! Maryland is about $3.28 a gallon right now! When I started driving I was paying $1.46 a gallon premium (1996 3000gt VR-4) and that was 8 years ago.

$2.92 seems so cheap now but it really isn't. Ridiculous...

I'll keep my eye open for 100% gasoline stations here in the Montgomery/Frederick County Area and post them up.

Um, not sure what you messed up there. But $1.33/L CAD = $4.90/gal US.