View Full Version : poor gas mileage


PewterNHRA2001
01-19-2006, 10:52 PM
i drive a 2001 trans am, all i have done is a lid and a borla cat-back, im averaging around 17-18mpg, i know that im not gonna great gas mileage in this car but still 17mpg? i drive about 30% city and 70% highway, usually keep the rpms around 1500 and 2000, rarely ever see 3000, i was thinking that perhaps new spark plugs may help seeing as how i have 70,000 miles and they have never been changed, also its winter right now(dont know how much impact that has) and my air filter hasnt been changed in a while but it still looks like new...any input as of to what i can do to get a little better gas mileage? what do others average? also would it be to crazy to think that i could get my mpg up to low 20's seeing how i drive mostly highway?

Ell Ess Won
01-19-2006, 11:59 PM
Don't complain, I get 14mpg city with only the mods in my sig. Some get even worse.

~RedLineLs1~
01-20-2006, 12:12 AM
change the plugs/wires and the fuel filter depending on the last time it was changed. Start from there...

LS1_Fonzie
01-20-2006, 12:15 AM
Are you using cheap fuel? I ask because I went from using premium fuel from Valero to premium fuel from Exxon. World of difference. I saw 300 miles from that tank and still had a little more to go compared to the 245 miles I was getting with Valero. Exxon is a little more expensive but worth it. I have the same mods (magnaflow catback & air lid) with a six speed and similar driving habits. Hope that helps.

SmokeySS
01-20-2006, 12:57 AM
I did a little gas mileage test on my stock 02 SS and was pretty sickened. It came out to 15mpg... What I was doing though was leaving it in D all around town and putting it into [D] after I had gotten on the highway. From now on I think I'll just leave it in [D] and re-calculate to check that it gets better.

Hoss Ghoul
01-20-2006, 02:53 AM
That is pretty bad mileage. I do about 75-80% highway, so close to your ratio.

With CAI and Magnaflow cat back wA4/2.73's I average 23-24 mpg. I have 33K miles, run 5w30 mobil 1 and live in a moderate temperature zone. I use 91octane Shell gas.

As mentioned above go ahead and change your fuel filter, check/replace you spark plugs and wires(if necessary), use higher quality/octane fuel...

Check to make sure your tires are properly inflated. They can look OK and be 10-15lbs under inflated. This is so often easily ignored/overlooked.

Hoss Ghoul
01-20-2006, 03:01 AM
One other thing to consider, this goes for everyone. So often I see threads like this and wonder how people are calculating fuel mileage...

One time checking it is not an accurate gauge. You must check it over at least 3 or 4 fill ups.

Also, I see alot of folks say they never get the tank near empty, etc. ...The point is, how are you calculating your mileage? I run my tank till it's near bone dry. I mean that when I fill up I put 15.8+ gallons into the tank. That increases accuracy for obvious reasons.

2kSnakeEater
01-20-2006, 09:00 AM
I get 16-18 in a 80% city driving, and thats with a few wot, car is a 2000 T/A and has 34k miles on thought dont know if milage has anything to do with it.

Clark Kent
01-20-2006, 09:41 AM
i usually get about the sam, .best tank was going to houston on full tank and got 333 miles to the tank.

jimmy 2 Times
01-20-2006, 02:02 PM
you put in 15.8 gallons????? the most i have ever put in was 14, and that was with the needle below E


btw, if you are in cold climates with emmissions, you may be getting "winter" gas, which is also known to kill MPG

PewterNHRA2001
01-20-2006, 11:39 PM
how much will new spark plugs cost, dont need anything special and of course dont want to spend a ton of money on them, with 70,000 miles should i have already done this? also i heard that it can be a little difficult to replace them, any tips or write ups to doing this? and lastly what benifits does replacing the plugs have on the engine? thanks in advanced

Ell Ess Won
01-20-2006, 11:59 PM
How I calculate my mileage is usually at 1/2 to 3/4 full tank, I take the number of miles I have on that tank, and fill the car up. Then I take how ever many gallons fit into the tank and divide that by the miles I got out of that much fuel.

Hoss Ghoul
01-21-2006, 12:34 AM
How I calculate my mileage is usually at 1/2 to 3/4 full tank, I take the number of miles I have on that tank, and fill the car up. Then I take how ever many gallons fit into the tank and divide that by the miles I got out of that much fuel.

That is a decent way to calculate mileage over the long haul...as in, many tanks. Otherwise it is an extremely small sample. Even one full tank is a relatively small sample.

Spark plugs are dirt cheap. They are tricky to change, be careful, an aluminum block is more likely to strip. Do a search, I'm sure you'll find a walk through, or buy a Haines manual. LS1 university may have a write up. Search the site, search google.

15.5+ is common, I've put over 16 gallons in multiple times. I run the car till it's close to dry and make sure I've spilled gas out of the tank while filling at least once or twice on every car I've owned or driven a significant amount of time...you have to learn the cars limits, in every way, lol...otherwise how do you know what you're doing?

01RedT/A
01-21-2006, 11:07 AM
16 gallons? thats incredible! i can run mine until the needle is practically resting on the bottom peg, and it MIGHT take 14.5 gallons. just goes to show you the inaccuracy of our gas gauges, which i s another common complaint. on more question? what is the factory spec for the size of our fuel tanks anyway??

92SilverSHO
01-21-2006, 12:32 PM
i have all of you beat!! i get about barely 13mpg in pure city. I think GM def overrated the city mileage for these cars bigtime. Im talking stoplights every 50ft kind of city like where i live now, not suburbia!

The Trans Am Kid
01-21-2006, 12:43 PM
Mine is bone stock and I get no more than 15 mpg. I put some fuel injector cleaner in the tank and it seemed to bring it to life. It sounded so much sharper. I don't know what it did for gas milage though.

Zymosis
01-21-2006, 01:07 PM
dont practice your 60 foot time at every stop light, keep revs below like 2500 and it will increase it some, I know w/ my setup I get about 15 mpg in town, but I always have to get on the loud pedal, and that sends it down to 11 ish w/ spirited driving :)

just make sure things like proper air pressure, fuel filter, air filter, plugs, wires, etc are good

you could also use seafoam / gm top end cleaner to get rid of some of the carbon buildup

Hoss Ghoul
01-21-2006, 01:50 PM
16 gallons? thats incredible! i can run mine until the needle is practically resting on the bottom peg, and it MIGHT take 14.5 gallons. just goes to show you the inaccuracy of our gas gauges, which i s another common complaint. on more question? what is the factory spec for the size of our fuel tanks anyway??

16.8 gallons.

I also run fuel injector cleaner through the car a few times a year.

92SilverSHO
01-21-2006, 01:55 PM
ive tried all the tricks, like they say, i granny drove it for awhile, but whats the point if the mileage isnt gonna go up! i was shifting under 2k, still didnt do anything for mileage, in the city, shifting that low, cars pass you because everyone gives it gas and the stoplights ever 50ft dont help either.

bandit12
01-21-2006, 08:27 PM
I had a 97 TA WS6 an routinely got 19 mpg city and 26 hwy. Of course it was a manual and that helps a bunch.

I now have an 04 GTO with a manual. The computer has me at 19-20 mpg. Went on a long trip last fall and got about 26.5 on three tanks.

v DaN 02
01-21-2006, 08:51 PM
my m6 got about 19 mpg all around when i first bought it.... but then i put a few miles on it... and gas milage went down... maybe new plugs would have cured it? whos to say?

mileage plays a role in gase mileage...

Reject
01-21-2006, 11:21 PM
couple of questions, the lines that run on the driver side of the frame, i think fuel return lines, if those are crushed will mpg go down? also where is the fuel filter on these cars? i get about 11 in town in OD

Camaro_Guy
01-21-2006, 11:28 PM
I average 15-16 in the city but I kind of have a heavy foot.

1LoudTA
01-22-2006, 12:17 AM
i get 170/180 to the tank, every week. 50/50 highway city. So 11mpg? It sucks!

Worst part is that my cam is going in real soon. That should definitly worsen it. :emb:

nomadnate
01-22-2006, 12:21 AM
with my m6 i measured my highway on a long road trip that took one whole tank on the trip and measured right at 27 mpg. gotta love that 6th gear

ChocoTaco369
01-31-2006, 10:10 PM
one word:

Seafoam

i did it to my 95 firebird with 78,000 miles and i gained 2mpg. granted, it's a V6, but you'll still see a difference. it was cool, i got to smoke out the entire highway. i pulled out of my friend's dad's car shop and blew blue smoke for a quarter mile. cars slammed onto their brakes driving into it. they were all watching me and cracking up.

it's only ~$5.00 a can at advance auto parts. suck it in through your brake booster and let it sit for 10 minutes. the instructions are on the can. it makes a world of difference, trust me. you won't be disappointed.

some of you guy's poor mileage is probably due to 80,000 miles worth of crap stuck in the cylinders.