I know gas mileage threads are endless .. and for that I'm sorry, but I've looked through a LOT of them recently, and cannot figure out why mine is so low. I calculated the last 3 tanks, and got around 17 mpg each tank.

I keep my car tuned up, just got the 90,000 service and keep oil changed every 3k. I drive more slowly than not, rpms rarely go higher than 3k; keep my tire pressure regulated at 31 psi; just replaced spark plugs, ignition coils, and maf; keep my a/c off; windows closed, everything I can think of.

I don't know much about the mechanics of the car, nor do I have another maxima around to compare mine to, so I really don't have any way to gauge if there is something wrong with my car.

Anybody have any ideas as to why my gas mileage could be so low?

 

Is this mixed driving?

 

Is that city or highway?

 

Try running some Auto-RX in your next oil change...

 

And you've pulled the codes and don't get a 0304?

 

Is it the same for 5th gnes

 

You may need to clean your IM. I know mine is pretty dirty now and my milage is around 23 on average. I'm waiting until this winter when I get to experience the joys of a 3.5 rebuild / build-up. My rings are fried and I'm losing oil like the Exon Valdez.

 

Mixed driving .. really about 50/50 highway/city driving on each of those tanks.
While I haven't run auto-rx or seafoam anywhere yet, I want to figure out what the problem is before I try either of them.
No codes have been thrown.
I looked in the FAQ and did a search, but the links in the FAQ are dead and my search for a how-to was, as usual, futile. Could someone please link me to a write-up for a 5.0 gen as to how to clean the IM?

Thanks for all your replies.

 

hell all i get is about 20mpg with my 6speed and i do the same 50/50 highway/city. My auto use to give me the same so i guess i am ok. When i took a trip to maryland i got like almost 30mpg

 

I know what you mean, i have 69k miles on an 01 5 speed, use synthetic oil with regular changes, ran seafoam through the brake booster line around 62k, dont hammer the throttle when i'm trying to get good miles, keep windows closed etc and i only get maybe 400-410/tank

 

I get about 17 myself & my car could not be better maintained. The poor mileage is pretty common in 2000 Maximas at least here in the north east. My poor mileage has been from day one & I only have 54000 miles on my car & I run Mobil 1 full synthetic tranny fuid & motor oil 5w30 every 4 months. I did a Auto - RX cycle & put 2 ounces in with every oil change & still I get poor mileage although I do more city than highway & drive fairly hard.

 

I don't think gas milage of 2000 max is that bad. I'm averaged for 24 mpg 50/50, sometime even got more than 26. On 100% highway gets high 27 cause I'm not a slow driver usally drives above 80. Otherwise I could get 28-29 easily.

 

So say I clean my intake, use auto rx, and still have low gas mileage. Any other common or uncommon reasons for such low gas mileage?
If I took it to the dealer would they find anything?
Am I just expecting to high (22ish) mpg?

.. don't mean to sound whiney .. but rereading that sounds like I am ... so uh .. yeah.

 

my auto has 117k and when i do 50/50 driving i get about 24 and all 80hwy/20city i get about 31. i don't do anything special just change my oil every 2.5-3k and put some fuel injector cleaner in. so you might wanna try fuel injector cleaner it does miracles sometimes.

 

I'm going to do fuel injector cleaner, seafoam, and/or auto-rx within the next week, but I think there is something else messed up with my car. I just have no idea what it is...

 

how are you determining your gas mileage?

Ive got a 2000 GXE with 5spd manual. I drive slow, don't rev it much. I have K&N drop in air-filter, I use synthetic oil, and synthetic gear oil in the tranny. I've got 80K miles on it and with 70/30 city/highway, I get around 25 mpg, and straight highway I can get up to 31 averaging 70 MPH. I run 25psi in my tires and I've installed an oil-catch can on it (it catches a surprising amount of oil). The last service I had was the 60K, and I replaced my spark plugs then too. The last thing I did was I cleaned the throttlebody myself not long ago. There was a ton of crap in there too. But I've never had gas mileage that bad...

 

mileage traveled (320mi) / gallons filled (13.756gal) = average mileage (mpg)

 

Mileage is lousy until the engine warms up. If your driving is a lot of short trips - even mixed city/highway - you will get awful mileage, especially during cold weather.

The trip meter of course does not give accurate mileage readings.. but, presumably you can use it for relative comparison. So that's what I have done for my trip to work, which is repeated frequently and in a variety of weather and traffic conditions.

I have an 8.5 mile drive to work. If I reset the mileage trip meter before starting the car and leaving home with a cold engine, I usually see about 24 mpg reported at the end of the trip (which I guess is actually about 19 or 20, given the approx. 20% inflation that seems to apply to the meter reading) Readings after the first 1.5~2 miles are frequently in the 15 mpg range or less.

If I stop at the gas station that is 0.1 mile from my house, and downhill at that - i.e. I have warmed up the engine for maybe 3 or 4 minutes while pulling out of the driveway, going downhill and pulling up to the pump - and then reset the meter, the mileage on the (now 8.4 mile) drive to work is usually about 26.

If the car happens to be warm from a previous trip, and I reset the meter before leaving home, I often see 28~29 mpg reported. (which probably works out to about 23 actual.)

My tank mileage (i.e. calculated based on measured miles and purchased gallons, not the trip meter) seems to run between 21 mpg summer, 18~19 winter. (If I make a highway trip it is much better, but that happens only 4 or 5 times per year, so I am leaving those out.) Winter trips often incur significantly longer traffic delays than summer so the difference is probably not entirely due to the change in temperature, but I'm pretty sure much of it is caused by the longer warm-up time.

My conclusion: that first 5-10 minutes, until the engine gets fully warm, the Maxima uses gasoline at close to 2 times its normal consumption. If the first 2 miles summer/4 miles winter is a significant percentage of your trip then your mileage is going to suck.

 

Not to hijack but how do you clean the throttlebody? Ive done it before a lot on a GM car, i didnt know if it was different for VI, just spray throttle body cleaner down there with the airbox off then run the engine??

 

Very intresting that would explain alot for me I live 4.7 miles from work. I usally travel less than 10 miles per day total 5 days a week. There are times when I only get around 215 to a tank.

 

On my last tank: miles driven (279.7) divided by gallons (15.589) = 17.9 mpg... which is above average for me
I can see why this would have some effect on my gas mileage as my commute is only about 8 minutes to school every day, but even then, that's a very small portion of my driving and I wouldn't think it would affect my gas mileage quite that much.

EDIT: carsarecool you have pm

 

My AE gets about 335-340 per tank it takes 16.5 or so to fill it (yes I run it real low) so I averaging 20-21 MPG. I run it pretty hard though. My friends think the drive it like you stole it sticker should have been modeled after me. It's 5sp, w/intake, Y-pipe, iridium IX's, profile says I have a Frankencar but not yet.

 

There has to be some type of hidden common problem with maximas, causing the miles per gallon to decrease instead of those common problems suchas airfilter, plugs etc. cuz i have that problem too. i get 16 MPG and i just changed my plugs, airfilter, tire pressure, tranny fluid, everything.!!AHH!!

 

holy 2 year old thread bump . . .

 

Bumping old threads doesn't increase your MPG....

 

But it does earn you time off.