# Poor Fuel Mileage



## mzr3yt (Oct 11, 2005)

Does anyone have any ideas as to why the GTO gets the gas mileage that it does? On the highway I am getting about 22 mpg. My '02 vette gets 31 mpg. What is the rearend ratio in a GTO. I know that the GTO is pushing more air, but 9 mpg difference between the two cars seems like a lot. What is the GTO's coefficient of drag? By the way, around town mileage is horrible (about 13 mpg)....but the weight of the car and my driving habits can probably explain that.


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## C5ORGTO (Dec 30, 2004)

I'm in the same boat man. Went from a 98 Vette which I got 16.5 in town driving, now i'm at 12mpg. I'm hoping it gets better once the engine is broke in. It is geared lower that the C5 at 65 in the Vette I was at 1250rpm, at 65 in sixth gear in the GTO its closer to 1500rpm. .


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## fergyflyer (Apr 18, 2005)

If you had an auto C5, the gear ratio was 2.73 rears or if you had the performance rear it was 3.15. Now you have a 3.46 rear. Stick versus stick the rear is the same, the tranny is slightly different. That would explain a small amount of difference. I'm not sure why the GTO gets such bad mileage. My 02 Z28 with an A4 and 3.08 gears with 335 RWHP got 29-30 on the highway and 19 in town. My Z06 C5 got 18 in town and 26-27 on the highway. The GTO is getting 17 city and 22-24 highway with the same type of driving. I think the weight has something to do with it, but that can't explain all of it. The CD is good for the GTO and matches the C5, but the GTO does have more frontal area. Still it shouldn't be such a large difference IMO. Oh well, I didn't buy the car for mileage, so I can live with it I guess.


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## BOSSGTO (Oct 5, 2005)

Same here. Went from a 01 C5 6spd getting 20 city and 30+ highway with a 3.42 rearend to 17 city and 22 highway in the A4 Goat. 

Higher frwy rpm, more weight, more drag and a shorter overdrive gear sux all the fuel.


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## mzr3yt (Oct 11, 2005)

So, changing the rear gear to a 3:08 and then installing different 1-3 gears in the transmission will allow similar lowend acceleration but provide better 4th gear fuel economy?


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## Groucho (Sep 11, 2004)

I probably have more seat time in the GTO than just about anyone in the US, and I can say without question that it's the around-town / slow traffic driving that kills the average mpg in these cars....I blame the work required to get two-tons of metal and glass moving...taking some care and shifting efficiently helps a lot. This car is fun to yank thru the gears, however, so that is exceedingly tough to do.

I seriously doubt dinking with the tall gear ratios will help much.

I have seen posts where some people claim 29 mpg averages...of course, some people claim they've seen Bigfoot as well.


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## 04m6_ca (Feb 27, 2005)

*19 - 21 mpg*

I commute 108 miles per day and a good 30 of that is in stop and go traffic. Avg speed for a tank of gas is 39mph and depending on how much I endulge when not in the bumper to bumper stuff, and I get 19 to 21mpg per tank. I took a road trip from Pleasanton CA to Pasadena CA, 350 miles, and did get 29mpg. I agree with Groucho, the stop and go really kills the mileage.


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## J.E.T. (Sep 30, 2005)

Mine is two weeks old now and is getting 20 mpg average. I'm quite happy with that........



JET


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## fergyflyer (Apr 18, 2005)

Just took an 800 mile trip. I found that if I set the cruise at 70 and turn the Valentine off (it just forces me to go) I get 25 mpg. At my normal 80-90 cruise I get 23. But about 250 miles of this trip was rural hwy with 55 mph speeds. I kept the cruise at 62 and was amazed to get 28.5 mpg. The computer showed 27.9 for that leg, but when I actually calculated it, 28.5 is what it was.


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## johnebgoode (Oct 4, 2005)

Mine is 1 week old and is getting 12 mpg. Its an improvement for me over my 2500 Subn. so I really dont mind it at all.


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## goat boy (Aug 17, 2005)

What a bunch of suck tits on here. you have a high performance car that weighs 3800 lbs and you complain about 22 miles per gallon? Good God, go get a toyota if that is your thing. My GTO gets better mileage than my 4 cylinder EVO. If you can't afford to put gas in it, look for another car.

Goat Boy


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## Groucho (Sep 11, 2004)

goat boy said:


> What a bunch of suck tits on here. you have a high performance car that weighs 3800 lbs and you complain about 22 miles per gallon? Good God, go get a toyota if that is your thing. My GTO gets better mileage than my 4 cylinder EVO. If you can't afford to put gas in it, look for another car.
> 
> Goat Boy


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## GTODEALER (Jan 7, 2005)

Groucho said:


>


My thoughts exactly..... where the hell do you get those pics? That sh*t is hilarious! :lol:


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## mzr3yt (Oct 11, 2005)

goat boy said:


> What a bunch of suck tits on here. you have a high performance car that weighs 3800 lbs and you complain about 22 miles per gallon? Good God, go get a toyota if that is your thing. My GTO gets better mileage than my 4 cylinder EVO. If you can't afford to put gas in it, look for another car.
> 
> Goat Boy


So why not get rid of your 3:46 gears and get some 4:56's......and while your at it, yank out your 6-speed and put a powerglide in.....and lower the tire pressure, and rip out the interior to save weight. All that matters is acceleration...right? 

I drive my cars everywhere, including 1,000 + mile road trips. If I can do something to get a couple more miles to the gallon, while more or less getting about the same acceleration....I will.


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## JWC (Jul 28, 2004)

With 5,200 miles on the clock, I have never gotten less than 18 mpg in town. The few road trips I took averaged 25 - 27. I have only "chirped" the tires once, so that tells you how little I jump on the go pedal. The six speed probably helps on the highway.


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## dvillar (May 6, 2005)

mzr3yt said:


> Does anyone have any ideas as to why the GTO gets the gas mileage that it does? On the highway I am getting about 22 mpg. My '02 vette gets 31 mpg. What is the rearend ratio in a GTO. I know that the GTO is pushing more air, but 9 mpg difference between the two cars seems like a lot. What is the GTO's coefficient of drag? By the way, around town mileage is horrible (about 13 mpg)....but the weight of the car and my driving habits can probably explain that.



You've gotot be kidding... I know I did'nt buy this car for fuel mileage;
don't get me wrong I'm not trying to knock anyone, but If you did ya probably bought the wrong car.... and besides 3.46 gears are lower, your making more horsepower than your 02 vette, and the vette weighs less. I know gas is expensive, but just drive and enjoy. :cheers


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## Grey-Goat (Jun 7, 2005)

How are you guys getting 12mpg around town??  I think I drive mine pretty hard but I've never seen my average down to 12mpg!! I average 16 to 17 around town.


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## C5ORGTO (Dec 30, 2004)

Does the gas mileage get better after you get some miles on it? I took a 400 mile trip this weekend, and got 21.5mpg. I'm still getting 12-13 around town, I hope after it breaks in it will get better. I've currently got 4,000 miles on my 04.


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## danrieke (Oct 12, 2005)

Took methodical approach to engine break-in on my new '05. See LS-2 Engine Break-In post of mine.

After 900 miles I'm getting avg. of 12.4 city, 21.4 hwy. I don't race hard, but can't resist pushing it frequently.

Seems this motor stock is going to get those figures on average. Next week my new KNN arrives so I'll let you know how that helps.


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## johnebgoode (Oct 4, 2005)

C5ORGTO said:


> Does the gas mileage get better after you get some miles on it? I took a 400 mile trip this weekend, and got 21.5mpg. I'm still getting 12-13 around town, I hope after it breaks in it will get better. I've currently got 4,000 miles on my 04.


Mlieage will ALWAYS get better as the engine breaks in. Std trans usually will do better than an auto.


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## Groucho (Sep 11, 2004)

danrieke said:


> Seems this motor stock is going to get those figures on average. Next week my new KNN arrives so I'll let you know how that helps.


Betchya money that, without a tune, you'll see an initial improvement then a steep decay in average MPG.

Betchya.


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## shadow (Sep 4, 2005)

*Mpg*

I use to go back and forth to work - 1 miles each way, 2 state highways. M6. Average speed always says around 30. I get 18 mpg. I am pleased with that. I have a 1991 Nissan 300ZX Twin Turbo which gets the same.


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## Jumbojet (Oct 12, 2005)

I'm getting around 9.6-10.5 MPG city with lights here and there. Overall mileage this weekend (city/highway-100miles) was 15mpg. I did do a few 3-4K shifts but most was normal driving with some passing on the freeway. So far I am dissappointed a bit but do realize the car only has 490miles on her. I didn't buy a 400hp car to get good mileage. I'm just a bit surprise at HOW bad it is. I had a 4450LB mid 13sec/101mph ImpalaSS with every bolt on(3200 stall/3.73's) and got much better mileage with alot of spirited driving(about 17mpg or better) JFYI. Once the car hits 1500-2500 miles I plan to switch to Royal Purple or Redline products and hope that helps a bit. If not I'll just stay out of the GO pedal a little more. Still loving this Beast! Jimmy.


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