Gas Mileage decrease - Newbies Forum

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Gas Mileage decrease
Thursday, February 10, 2005 2:07 PM
I have an 03 cav with 27500 miles on it and I used to be able to get 400 miles off of one tank of gas. Now just recently I have been only getting about 350 miles out of a tank. I change the oil about every 4500 miles, is there anything else that could be causing this decrease? I have been driving it the same way as I always have been and I dont use the A/C, any ideas? Thanks!


"A car isnt just used from getting from point A to point B, it is the point"

Re: Gas Mileage decrease
Thursday, February 10, 2005 2:18 PM
maybe a new pump and fuel filter would help



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Re: Gas Mileage decrease
Thursday, February 10, 2005 5:57 PM
The cold can eat up gas more.....and you shouldn't allow your tank to get to low as in cold temps it xcan build moisture in your tank......


I have one true love in my life...And my girlfriend sits next to me in it
Re: Gas Mileage decrease
Thursday, February 10, 2005 7:26 PM
You're getting 350? My Cavalier is an 03 as well pushing about 46,000 miles and I still make about 420 a tank, but that's down from the 450 I made when I got the car. There could be a few things that could effect your gas mileage. Fuel pump and filter could be one thing. Another thing could be the way you drive, especially if your hard on your Cavalier. Also, have the air filter replaced if you haven't done so already. I know it may not seem like a big deal, but I had my air filter replaced at 30,000 miles and the extra miles I was getting on one tank of gas increased by about 45 for the short term and dwindled down to about 25. I think on the first tank after I replaced the air filter I got 475 miles, but of course that's just me, and I also put an extra gallon of gas in my car when the pump cuts off, usually at 13.7 gallons. Also if you let your car idle (warming up the inside, defrosting the windows, so forth) alot that can decrease gas mileage. I think I read on a post somewher that said something to the effect of: "If you are letting your car idle, you are getting 0 gas mileage" or something which is true. These are the only things I can think of, at the moment. If push comes to shove, you can always take it a mechanic, if you have that type of dough.
Re: Gas Mileage decrease
Thursday, February 10, 2005 8:28 PM
I average at about 570 Kilometers though what woudl that be in miles......2002 ecotec


I have one true love in my life...And my girlfriend sits next to me in it
Re: Gas Mileage decrease
Thursday, February 10, 2005 8:34 PM
I think that's about 354 miles...not sure, my math is a little fuzzy, I'm not quite certain on the kilometer to mile conversion but I think 1 kilometer is equivalent to .65 of a mile, but I could be wrong, like I said, my math is fuzzy.
Re: Gas Mileage decrease
Friday, February 11, 2005 12:15 PM
Does the elevation make a difference on the gas mileage? Like if you drove your car at sea level compared to up in the mountains? I think it would just have an affect on the amount of gas your tank could hold because of the pressure differences right?

Also, 570 kilometers = 354.18158 miles
1 kilometer = 0.621371192 miles




"A car isnt just used from getting from point A to point B, it is the point"
Re: Gas Mileage decrease
Friday, February 11, 2005 1:53 PM
^ ^ ^ ^ ^ ^ ^ ^ ^
It's possible, but I can't be certain. Also, I guess I should say my car is almost exclusively driven on highways/expressways/interstates at about 400 - 425 mles weekly. So if you drive your car mostly through town at slower speeds then I wouldn't worry about it. I noticed when I was on Christmas Break from work, my gas mileage was lower than it usually was when I drive to work.
Re: Gas Mileage decrease
Friday, February 11, 2005 3:11 PM
Figure your actual MPG instead of just your miles per tank. Are you putting the same amount of gas back in each time? What I'm getting at is that unless you are really paying attention to how many gallons of gas along with the mileage, how are you determining that you are out of fuel? I know as my car aged, my gas gauge got worse and worse on showing how much fuel I really have.




Re: Gas Mileage decrease
Friday, February 11, 2005 5:12 PM
i got a lemon car. 2002 sunfire gt auto. 250 miles to the tank on a good day. thats from full tank until the gas light is on. not a heavy foot either


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Re: Gas Mileage decrease
Friday, February 11, 2005 9:16 PM
Mine gets any where from 19-21 mpg but thats driven around tha country and not that much on the highways. My old 98 Z24 used to get 20-22mpg but I am harder on the newer one.


2000 Z-24
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Re: Gas Mileage decrease
Friday, February 11, 2005 11:33 PM
Jackass wrote:Figure your actual MPG instead of just your miles per tank. Are you putting the same amount of gas back in each time? What I'm getting at is that unless you are really paying attention to how many gallons of gas along with the mileage, how are you determining that you are out of fuel? I know as my car aged, my gas gauge got worse and worse on showing how much fuel I really have.


My actual MPG is about 28 - 30 miles per gallon depending on driving habits and other criteria. On average I put between 14.5 and 15.0 gallons (maybe a little more) in my tank, after the pump initially cuts off, i'll put an additional gallon. I actually do pay attention to my miles per gallon, and I've had my car for two years already and it hasn't dropped significantly. I dropped a little but gained most of my mpg back when I changed my air filter back a few months ago. Actually my miles per tank and miles per gallon actually sucked when I got my car as I was averaging 350, but slowly over time it rose. I'm pretty good at predicting how far I can go on a take of gas before I absolutely need to refill. Trust me, I'm one of those drivers who are constantly monitoring the needle, my gas mileage and where they are and where they should be.
Re: Gas Mileage decrease
Saturday, February 12, 2005 4:44 AM
Geez, driving to Cali in my 2000 Z24 I was getting almost 500 miles to a tank....I guess I have a good car.


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Re: Gas Mileage decrease
Saturday, February 12, 2005 6:44 PM
it is really cold where you live I mean like freezing? In the winter they add as much alcohol as they legaly can to change the freezing point and it burns faster. Also your car general runs richer in colder weather. Try a premum fuel from a good gas station like mobil or shell.




1979 Impala Sport Coupe Aeroback
Re: Gas Mileage decrease
Sunday, February 13, 2005 7:23 AM
Best I ever did with my eco was 440 to a tank, now I have an LS sport which is alot heavier than a base model 03+, however best I've done since then is 400, now once I go above 65 it really begins to go downhill as far as gas mileage, most of my trips I do between 75-80 which means I only get maybe 350 to a tank, and when I'm really flooring it having fun around town I get about 250. My fuel filter is prob needing replaced again and my injects could prob be replaced, I'll be adding the MSD DIS 2 on soon which should bump up the fuel mileage again



1989 Turbo Trans Am #82, 2007 Cobalt SS G85





Re: Gas Mileage decrease
Sunday, February 13, 2005 9:34 AM
Damn i'm always flooring my car but i never taught it made that big of a difference
Re: Gas Mileage decrease
Sunday, February 13, 2005 9:45 AM
Gaylord @!#$er wrote:Damn i'm always flooring my car but i never taught it made that big of a difference


Flooring it makes a HUGE difference.

I went through a quarter of a tank at the track in less than 20 runs. So including the braking portion and the drive back, that's around 15 miles... so that would be about 60 miles to the full tank... and that's only at full throttle about a third of the time.






Re: Gas Mileage decrease
Sunday, February 13, 2005 2:53 PM
icee_smooth_cavalier wrote:My actual MPG is about 28 - 30 miles per gallon depending on driving habits and other criteria.
Which is about right where it should be.
icee_smooth_cavalier wrote:On average I put between 14.5 and 15.0 gallons (maybe a little more) in my tank, after the pump initially cuts off, i'll put an additional gallon.
Not sure how you put that much in since our tanks should be just a little smaller than 14 gal (at least my '99 is). And your not supposed to really top off your tank either. Quite often it just dumps out of the overflow or gets sucked back up the vapor recovery things on the pumps (if your region happens to have those).
icee_smooth_cavalier wrote:drivers who are constantly monitoring the needle
Never just trust your gas guage. Mine hasn't worked correctly for the past 3 years. I'll have 250 miles on a tank and the needle shows 3/4 full. It is a fairly common problem for the guages to get less and less accurate as the car ages.
Then again, maybe I am just jealous that some of you are getting 400+ miles out of a tank when the best I can get is about 360 driving very nicely.





Re: Gas Mileage decrease
Sunday, February 13, 2005 3:32 PM
Jackass wrote:Not sure how you put that much in since our tanks should be just a little smaller than 14 gal (at least my '99 is). And your not supposed to really top off your tank either. Quite often it just dumps out of the overflow or gets sucked back up the vapor recovery things on the pumps (if your region happens to have those).


Well I'm not sure if the gas tanks were changed between your generation of cars and the current models or if my car is a freak, but I know my car can handle 15 gallons easily without anything flowing over or spilling elsewhere. I think it's listed in my manual, on the Chevrolet website or someplace that the tank size for the +03 Cavaliers is a little over 14 gallons (14.1 to be exact I think) so my tank isn't smaller than 14 gallons. Putting an extra gallon in my car after the pump stops will not over flow my tank or has cause any other damage to my car, (well I haven't noticed anything or any problems yet) and I'm almost willing to bet it's a common practice with others as well (my bestfriend does it in her Celica which has a slightly "bigger" gas tank) and not just Cavalier owners. I've only really topped off my gas tank once and that occured when my car completely ran out of gas, but I was fortunate enough to be near a gas station. On that night, I filled my car to full capacity to see how much gas it could hold. The pump cut the tank off at 14.3-something but once it did that, I kept filling up until my car could no longer hold any more gas and when I was done, I had managed to put a little over 16 gallons in my car, believe it or not. I haven't put that much gas in my tank since as I noticed my gas mileage was pretty much the same putting in 16 gallons as it was with just 15 gallons. Like I said the pump usually cuts me off at 13.7 gallons or so and I'll put an extra gallon or so in my car after it cuts off. Putting around 15 gallons in my car everytime I fill up hasn't hurt it yet, and don't see any reason why I would need to stop. It's not really topping off, or over filling especially when I learned the tank can handle so much more gas than what I usually put in.
Re: Gas Mileage decrease
Monday, February 14, 2005 2:49 PM
Ive never fit above 13 in mine with the fuel light on, I think the capacity is 13.1 on an ls sport



1989 Turbo Trans Am #82, 2007 Cobalt SS G85





Re: Gas Mileage decrease
Monday, February 14, 2005 7:07 PM
I've got a 5 speed 02 2.4liter Z with a K&N filter and a flowmaster muffler. I think the tank is rated at 14 gallons, and I average around 25 mpg based on the gallons of gas I put in. Thats trying to drive nicely on both the highway and around town. I was hoping for better, but then again, 25 mpg is is a lot better than my '99 GMC Sierra's 15 mpg. Plus the Cavi is a lot more fun to drive.




Gotta keep on livin', L-I-V-I-N

Re: Gas Mileage decrease
Monday, May 30, 2011 11:19 PM
i get about 450miles a tank without overfilling it ,... ive drove from tulsa oklahoma to abilene texas on 1 tank of gas and still able to drive some more.. with my 200$ cavvy lol



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