I have been trying over the past week to see how good on gas I could get, and I am interested in knowing how accurate the gauge is. Here is the scenario:

I am getting exactly 21.0 mpg. I have gone 265 miles so far on the tank, and it says I have around 75 more miles before emtpy.

If it is a 20 gallon tank, 21 x 20 = 420 miles per fillup

But as of now I will only be getting 340 miles per fillup.

Is the gas tank really 20 gallons or does the gauge like to tease me?

Anyone else try to do this?

 

I dont think that the tank is twenty gallons, I have never put more than 13 into my tank.

 

The mileage gauge is fairly accurate, but I noticed that it is usually on the conservative side. Mine would read about 21 mpg while I'd be getting over 22. The DTE meter is also really conservative, you can drive once it is past 0, once you get to that point you have about 3 gallons left.

 

Are you taking into account the 3.5 gals or so that the DTE lies about. The DTE says you are empty when you have about 3.5 gallons of gas left (not sure exactly.. and the damn manual doesn't say).

So, if you are filling up as soon as the little light comes on, then you're math would really be:

21 x 16.5 = 346.5

If you're getting 21 miles per gallon, you should be able to drive around for another 73.5 miles without running out of gas.

And this is why I hate that damn DTE guage.. I wish it would tell me how much gas I really have instead of padding it so I don't make a mistake. Grrrrr...

I know your question was about MPG guage, but I think it is somehow related to the DTE in that the MPG takes those few gallons into account, too.. but I can't exactly remember my theory about that right now....

 

That still leaves the question, do we really have 20 gallon tanks on our cars?

 

Manual will tell how many gallons the tank holds.

To calculate mileage, take mileage from last fillup/gallons to first click on next fill up. Mine shows the car MPG gauge to be off by about 2 to 3 mpg.

 

I have filled up 17 gallons before. I believe if u take all the gas out of our tanks and filled it up it would be very close to 20 gallons

 

From Nissan website:

Fuel tank (gals.) 20.0
Engine oil (qts.) 5.0 max

This makes me beg to ask the question..WHY SUCH A LARGE FUEL TANK AND WHY AM I ONLY GETTING ~300 MILES PER FILLUP ON A 20 GALLON TANK!

 

Rob, do you actually fill your tank up with 17 gallons or 20? I get about 300 miles per tank, but I fill it up when I have 3 gallons left. 300 / 17 = 17-18 miles per gallon.

Also, your Z's empty fuel tank light will come on when there's 3 gallons left.

 

I don't fill it up when the light turns on but BigBadBuford said you actually still have 3 gallons left when your DTE reads 0

 

I am getting 256, be happy with 300.

 

It is obvious that Nissan has a built-in cusion so that you could begin looking for a gas station when the DTE reads 0. If they tried to make it exact and you ran out of gas on the interstate when the DTE read 1 mile, well......

WayneTN

 

Man, I'm getting 14.2 miles a gallon with my automatic. I drive to and from work in traffic, but that is still pretty bad. I don't peel out or beat on the car. Could 14.2 be correct?

 

I doubt if that is correct - calculate the old way, fill up, reset trip meter, then on next fill - divide milesage driven with no of gallons used. I will be extremely interested in your results.
Lee
Mlee13@qwest.net

 

I'll try it that way. Either my car is bad on gas or my computer is crap.

 

You do know you have to reset the computer to get your mpg right? You cant just "click" to it and it is right, the car has to factor the speed at which you drive, etc.

 

I realized this exact same this morning when driving into the office. kept thinking those bastards at Nissan are a bunch of liars, 19 mpg my ***. I then realized that I can reset it and came to conclude that I need to reset after every refill. unfortunately I filled up last night and reset this moring so this one is out the window. I have noticed though that stop and go traffic kicks this cars buty, of course it could be that I'm more observant since I have this feature now for the first time. I'm not taking it as gospel, but i am heeding it. I usually get around 250 when I hit 1/4 tank line, I don't allow it to get under that. My luck I'll be stuck in BFE and no one to contact.

P.S. i just did some quick math and
the last time I filled up I put in 11 Gallons, went 250 miles or so. this equates to ======22.72 mpg.........not bad

 

Try this, on the way to work one morning set your cruise at 60mph. Reset the computer and watch yourself get 31mpg.

 

I dont believe it's constantly measuring your gas tank level - it is measuring the consumption going through your fuel line and calculating that against miles driven. ( both of which are reset when you use the lower control on the right hand side of your instrument panel ). You can reset that at any time and it will then start calculating at that point until you reset it agin.
I didnt reset mine unil about the 3rd fill- up , by that time my mpg was increasing because I was becoming a better driver with the 6 speed. I had been off the stick since I sold the 300 in 1995 and I needed a bit of re-educating on the shifting - and the 6 being noticably different from the 5.

 

Mine isnt to accurate.