Does anyone get worse MPG than this? (pics)

[Brian35XR]

On a recent fillup I had to take a picture of this. 200 miles on a full tank.



Do I win the award?

[TDot]

No award for you, I get 192.

On that note, unplug your battery over night (I did it for the weekend) after you fill up. Run that to empty and then refill and you should see the proper fuel economy.

I had to do this because I was doing excessive idling. I don't know if it truly worked because after the second fill up (which got me seeing my fuel economy what it was 3 years ago before all the idling at 225) I had to do a lot of idling again which put me back to 192. Once I'm done with all my gadget repairs, I'll see how this experiment pans out with no excessive idling after 3 or 4 refills.

[steelcity]

Wow thats brutal. What mods do you have Tdot?

[The00Dustin]

TDot, are you suggesting that the reset button on the fuel economy doesn't give you a consistent reading if you reset it each time you fill up, or that excessive idling messed something up? In the former case, I find that difficult to believe. In the latter case, I would expect one of the reset procedures (such as the idle air relearn, for instance) discussed elsewhere in these forums to help as much or more, but certainly could be wrong.

[TDot]

The reset button consistently gave me the wrong number, 192....or the car was constantly burning fuel to the point where my number was 192 no matter what after the fact. I don't know. Al I know is the reset button did nothing for me in giving me what my mpg should be even if I drove like an angel for two complete fill ups. The only thing that worked was to unplug the battery over the weekend after a fill up. I couldn't be bothered with all that pulling, pushing, timing reset stuff...just unplug and done, much easier.

No performance mods.

[Ilya]

The car learns the fuel map too...so if you do tons of idling like TDot, it might have set itself up for such 'use'.

If you have an ODBII computer (nice one), you can sometimes clear learned ECU parameters. I know I can do it with UpRev (specifically says 'clear learned Fuel map').

[BizAsUz]

Mine was 17.5 then dropped down to 17.1 because during the winter months I start my car in the mornings and let warm up before I leave...so I guess the idling everyday contributed to the drop... not sure why in your case...

[The00Dustin]

192 is the DTE. If the DTE on a full tank is 192 but you can drive further than that consistently before the needle gets to E, that could be due to some other issue (bad reading on the tank fill, who knows what else), so resetting everything by pulling the battery makes sense. 192 is NOT MPG. The second number is MPG, in the picture above it is 13.8. This number is averaged for the entire time the engine is running after it is reset, so if it isn't reset, it will be affected less and less by how you drive. The DTE number (200 in the picture above) is based on something else, like the last 15 miles/minutes (I don't know exactly what, but the number will bounce all over the place based on how you have recently been driving), so if you always drove the same way to the same gas station and it took enough time/distance, you would always come up with a similar DTE after filling up, but in that case, disconnecting the battery would have no effect on the next trip to the station.

[TOMatBMR]

My display has consistently shown 16.6 since I bought the car. I was hoping to get around 20 but no luck.

[Ilya]

What is the manually calculated MPG (number of gallons filled/number of miles driven)?

[BizAsUz]

My display has consistently shown 16.6 since I bought the car. I was hoping to get around 20 but no luck.

for you.... you might want to reset the MPG counter in the options. it may or may not make a difference. if your driving habits are better then the previous owner then the MPG should go be better than what you have now...
also I assume that if you are using premium octane gas that helps with fuel economy.

[Ilya]

Here is a thread for some other suggestions that can help improve gas mileage:

gas-mpg-s-what-can-we-do-t529082.html

[TOMatBMR]

Here is a thread for some other suggestions that can help improve gas mileage:

gas-mpg-s-what-can-we-do-t529082.html

I will check that out, thank you!

[TOMatBMR]

My display has consistently shown 16.6 since I bought the car. I was hoping to get around 20 but no luck.

for you.... you might want to reset the MPG counter in the options. it may or may not make a difference. if your driving habits are better then the previous owner then the MPG should go be better than what you have now...
also I assume that if you are using premium octane gas that helps with fuel economy.

Yeah I reset it and still end up at the same.

[Brian35XR]

What is the manually calculated MPG (number of gallons filled/number of miles driven)?

Here's a pic I just took now that my tank has gone empty. The needle looks like it's at an 1/8th of a tank because I'm taking it from the left angle but it's really nearly touching the E line.



So I realistically get around ~220miles/tank? Is that completely acceptable or should I start looking at my car funny... 11 MPG?

[Ilya]

Do the math manually to get an exact number for MPG (unless you know how many gallons you filled up last time from empty and divide 218 by that). Here is what I would do:

1) Wait till the next time you're basically on E again (preferably with light on)
2) Fill up full tank and write down number of gallons you filled up and also your mileage
3) Drive to E/light again and write down how many miles you went
4) Divide the number of miles you went in #3 by the number of gallons you filled up in #2.

Let us know that number.

220 isn't insanely bad. It's not great, but it's not bad. I used to get like 270 on my M35 and get about 300 on my M56 (thanks to the 7AT gearbox - better RPMs).

If you are indeed getting 200 or below, then I'd look at the thread I posted above to make sure your car is in proper maintenance shape, tire pressures, etc. Even little things like a stuck caliper could be causing drag and affecting your mileage. I run my tires at abour 37psi (in that thread I mention 33).

[Larz]

I think it's best to consider the computerized AVG mpg the way we consider the EPA ratings. It's useful for comparison before and after change driving habits and style, drive different roadways, etc. EG: When you shop for a car, you compare the EPA estimates. You know full-stop you won't get that exact mileage when you drive it, but its useful info when deciding between a car with an EPA of 15 city Vs 19 city. When you see the avge mpg, it's based on a ginormous amount of data - not simply how many miles traveled on how many gallons burned. It also includes time spent at stop lights, amount of gas used starting off on a green light, time spent at idle, coasting, wind, tire condition, etc etc - all of which effects mpg. Whilst driving, if I push the reset button on my NAV screen, the mpg goes to 0 and re-starts the calculation. At first it is usually high, then gradually goes down as I continue to drive. If that particular drive did not involve stop-and-go traffic, or long red light delays, it usually ends up somewhere around 19. If I reset it whilst driving on the motorway with cruise control it usually stays above 25 and goes back down after I return to surface streets. Mostly it is around 18 on any given day. I chalk that up to unavoidable gas hogging situations - stuck at draw bridges for 6-10 min with the air con running, slow driving pensioners in front of me, heavy traffic, stop lights, and of course my right foot is heavier than my left foot whilst driving, LOL. I must say though this 7 sp gearbox has reduced my fuel use by nearly 2 fuel fill-ups on treks to Maryland - one less tank each way. I reckon I get around 275 miles day-to-day driving and over 350 miles on sustained motorway driving (2500 rpm gets me nearly 75 mph with cruise control).

[The00Dustin]

Ilyakol's method gives you the average MPG for a tank and will only be off by the difference in how full the tank got between the two fillups (minor differences due to angle of the ground, temperature inside the tank at fillup, etc). The computer is trying to calculate the average MPG for whatever you tell it, but it can't measure the gallons that precisely, so it uses other factors out of necessity, not because it's a better method. It's higher if you reset it when you're driving because getting up to speed wasn't factored in. In other words, if you reset the average when the car is off and fill up the tank, the division trick should give you the same number as the number on the screen, but the computers don't always get it right. Some are always high, some are always low, and some start out right but end up wrong. Mine was right following that procedure for the first few years after I bought my M, but in the last few years, it is always ~1 MPG high with summer gas and ~1 MPG low with winter gas. Presumably something could be repaired or replaced to get it back to accurate, but I don't know what.

[Ilya]

Ilyakol's method gives you the average MPG for a tank and will only be off by the difference in how full the tank got between the two fillups (minor differences due to angle of the ground, temperature inside the tank at fillup, etc). The computer is trying to calculate the average MPG for whatever you tell it, but it can't measure the gallons that precisely, so it uses other factors out of necessity, not because it's a better method. It's higher if you reset it when you're driving because getting up to speed wasn't factored in. In other words, if you reset the average when the car is off and fill up the tank, the division trick should give you the same number as the number on the screen, but the computers don't always get it right. Some are always high, some are always low, and some start out right but end up wrong. Mine was right following that procedure for the first few years after I bought my M, but in the last few years, it is always ~1 MPG high with summer gas and ~1 MPG low with winter gas. Presumably something could be repaired or replaced to get it back to accurate, but I don't know what.

Regarding your last bit...you DO get worse MPG's with winter gas. That's a known side effect of the 'winter mix'. I usually get 17-18 during the winter and 19-20 in the summer. It's been that way on all my cars since I started driving...97 Maxima, 99 Maxima, 07 M, 11 M, etc.

[The00Dustin]

Regarding your last bit...you DO get worse MPG's with winter gas. That's a known side effect of the 'winter mix'. I usually get 17-18 during the winter and 19-20 in the summer. It's been that way on all my cars since I started driving...97 Maxima, 99 Maxima, 07 M, 11 M, etc.

I know that, but what I meant is this:

With winter gas:
The computer says I get 18, but the calculator says I get 19.

With summer gas:
The computer says I get 21, but I get 20.

This is consistent across dozens of tanks throughout the season.

[Ilya]

Oh, okay. Gotcha.

[TOMatBMR]

I filled up this morning and meant to reset my odometer and completely forgot about it until I got to work. Oh well, next time!

[cruzad3r]

start writing down the mileage every time you refill and do that consistently for about 4-6 weeks. that should give you a good indication of what you're using.

i can show you records dated back to the early 2000 for all of my car. it's a great way for me to know if my car is performing as expected or something is up.

btw - summer with mostly city and limited highway driving for me will yield between 17-19MPG - If i drive the whole tank on the highway i can get between 20-22 MPG (depending on the cruising speed)

Winter is horrible - it can go down to as low as 14 and rarely see anything higher than 18MPG.

[scott23642]

I see the same when my new 16yo driver gets behind the wheel without me! Never with my driving do I see those numbers.

[mikew83]

I'm averaging about 17-18 here in the summer. With a mix of A/C and windows open, and city/highway travel. I always reset my trip A when I fillup, so it seems that the cars MPG calc is spot on. I roughly get 300 miles to a tank. This last one I got 317 before I decided it was REALLY time to go to the gas station lol. Premium only, and new tires. So that might help contribute to better #'s.

What I do is, look at my trip computer after I fill and before I clear it. Divide the 300 odd miles by how many gallons it took me to fill the tank with. The value I get is always identical to what the car is telling me my average is. Now that being said, I'm still rather ticked off that I gave up my super smooth and fast Q45 for a V6 M, considering my Q got the exact same MPG as this bad boy...

[cujonz]

City driving I average around 400km (250mi) to a tank. That's 6.6km/l according to my car, which is apparently around 15.5mpg. That's pretty short runs (about 10km) home to work and back twice a day.

Long distance, working really hard to keep my foot light I managed to average 12.6km/l over a distance of 200km. That's almost 30mpg.

Same distance, not trying so hard, I can easily manage around 11km/l or 26mpg.

The best distance to empty I've seen was when I filled up right after the 30mpg run - Can't remember what it was exactly, but it was high 900s, almost 1000km to empty!

[bakili]

Reviving a summer thred now. So I might be beating everyone at "The worst gas miliage" award. Max I'm getting is 13.4 driving like an old lady with bad vision, mostly local city driving and very little highway. I just bought the car (with 89K miles) 1 month ago and I love it regardless. What I did to it is:

1.Megan Axle backs / 2. Z-tube / 3. K&N drop in filter / 4. Changed all sparkplug to platinum laser OEM .44 gap / 5. Oil changed to Royal purple with Wix filter / 6. Brand new Kumho ecsta LX platinum (19" sport wheels)

I did reset MPG counter in M35 system, couple of times took batter out for few minutes to clear all info. The very first time filled up Chevron Techron, now using Shell premium. Any ideas guys why I'm getting such lousy gas miliage?

p.s. planning on taking a trip from SF to LA this X-mas, so curiour how that will work out.

[cruzad3r]

same advise, consistently write down mileage and gallon used for 4-6 weeks then do the manual calculation.

also the plugs should be gapped at .43 not .44 per manual.

what is your tire pressure at?

[Wangtang408]

Reviving a summer thred now. So I might be beating everyone at "The worst gas miliage" award. Max I'm getting is 13.4 driving like an old lady with bad vision, mostly local city driving and very little highway. I just bought the car (with 89K miles) 1 month ago and I love it regardless. What I did to it is:

1.Megan Axle backs / 2. Z-tube / 3. K&N drop in filter / 4. Changed all sparkplug to platinum laser OEM .44 gap / 5. Oil changed to Royal purple with Wix filter / 6. Brand new Kumho ecsta LX platinum (19" sport wheels)

I did reset MPG counter in M35 system, couple of times took batter out for few minutes to clear all info. The very first time filled up Chevron Techron, now using Shell premium. Any ideas guys why I'm getting such lousy gas miliage?

p.s. planning on taking a trip from SF to LA this X-mas, so curiour how that will work out.

I did a trip from San Jose to OC on a full tank with little less than a quarter to spare, avg 27 miles a gallon, I got 400 miles before I filled up.

[kmiles]

Over Thanksgiving we drove to SLC from Seattle. Most of Idaho and Utah are 80mph. I averaged 72.6 MPH over the entire trip and gas mileage was 21.6 mpg. Part of the trip we were fully loaded with wife, daughter and two little grandchildren and a fully packed trunk. The car ran great. Worst part of the trip was an unexpected snowstorm through the Salt Lake valley. The AWD and the new Michelin Pilot A/S 3's didn't slip at all. We saw over 50 wrecks on I-15 in a 45 mile stretch. We went about 350 miles per tank, but I didn't let it drop below 1/4 of a tank due to the winter weather. When we left Idaho it was -7 and the car started right up.