No, that's not what I observed on my 06 FEH.

The Miles to Empty reflected the displayed average MPG and the internal calculation used that number to multiply the measured fuel level in the tank to get to MTE.

While it's true that the calculation of MTE will drop to zero when the fuel tank is empty (of course it does if that side of the calculation is zero) that doesn't mean you can trust the displayed MTE. It just means that the error drops to zero... when the tank is empty!

But you cannot do any real planning as a result of this, you have to run your own numbers manually. If you're on the interstate and the next exit with gas is 50 miles away and your display tells you that you can make it, what good is it if you actually run out of gas at 45 miles and the display got to zero a few miles ago.

If you use a faulty MPG in the calculation you get a faulty MTE on the display.

That is precisely what I saw this summer.

 

So yes, you and I see the same thing!
( I don't know why the communication process is having difficulty. )

You said what I said.
On a full tank, the MTE will read much too high when towing.
On a nearly empty tank, the MTE will read only a few miles too high.
You were implying before that the MTE would start at 400 and be at 200 when you ran out of gas. This is not the case.

Normally I drive 30 miles past zero.
Towing, I drive 15 miles past zero, because I know the MPG is lower.

 

No, you phrased your posts to imply that the calculation inside the computer was more accurate because of the fuel gauge input to the calculation.

That's not true. Just because the error gets smaller as empty is approached doesn't mean the incorrect calculation is more accurate as empty is approached, it simply means the error is smaller as zero becomes closer.

That's how the math works out. (eg MPG X Fuel level = MTE... as one term approaches zero the result does the same regardless of the other term)

A person that relied upon the MTE reading to get to the next gas station could be left short. Envision a 10% high error. At 100 miles you would really have 90 miles of fuel. So if you rely on that you really run out of gas 10 miles short. The fact that the absolute value of the error got smaller as empty was approached doesn't help someone on I-80 between mile marker 311 and 215 in Wyoming.

Yeah, yeah I know about the "reserve," many people rely on that as a cushion and run right by gas stations...

 

Please go back and re-read my posts. You'll find nothing incorrect.
Maybe not to your liking, but nothing factually wrong.
You are rambling on and on and are being rude.
Why do you keep reposting what I already posted and trying to say I'm somehow wrong and only you're right?

I've drivin this car probably more miles than you, (85K) more years than you, under more diverse conditions than you, and I think I explain things accurately and without being rude to others.

Forget the remedial math, you are being offensive to myself and other well educated persons who frequent this site.

Either your car is different than mine, or you can't come off your soapbox to see the forest though the trees.

 

The rudeness is yours my friend...

If you were truly saying the same thing, why did you post at all? Yours was completely unnecessary, coming as it did after my initial post of what I observed.

I have read your posts and they are designed to cause an inference different than you propose, sorry.

And it appears that your math could use a brushup or at least your understanding of % error as reflected in smaller numbers.

After reading the Owners Manual I discovered the real answer: when you need to, reset the MPG counter. When in the MPG display, hold the reset button down for 2 seconds.

Best of Luck.

 

The extra gas might be needed in the tank to keep the fuel pump cool, if the FEH follows the same design as other cars.

 

Bill, I don't think that resets the MTE, it only resets the average MPG. The MTE uses its own calculated MPG, which is some kind of running average. The proof is that if you reset your MPG, the MTE won't change.

One thing I'm not sure of is if the MTE only changes when fuel is added, that is, if I had bad MPG on my average meter, and I fill up but then have much better MPG, will the MTE increase? I don't really watch MTE, so I can't say if it extends, or just calculates it once at fill up and then counts down the miles.

 

JTsyo: if this is like my Mustang the fuel pump is suspended in a container that holds maybe a half gallon of gas. If I'm right there is a bleed from the pump output that keeps this full for the cooling you speak of.

So you're right that they want the pump kept cool.

stevedebi: I've only reset once and the MPG went way up. I had already started the engine so when I started out I was on the battery and mileage went to 99.9mpg. The MTE went similarly way up. Since I didn't discover the reset until this recent drill, I haven't watched it enough to say much.

I should have looked this up last summer when I really needed it (you know, duh-h-h, I should have known there would be a reset feature).

I'll have to watch it closely now. I am so used to tracking fuel (I maintain a spreadsheet with every purchase, gallons, & odometer) I know pretty well what mileage to expect. Also I pay attention to where the fuel gauge is so I have a decent idea how much fuel remains in the tank for a given needle position and can tell if consumption has changed. Given this I don't rely on an MTE readout much.

Deal! I'll watch it.

 

The reset only resets the MPG shown for the user.
It does NOT reset the internal calc for MTE.
Proof: if true, anyone could get a photo of a value higher than the one shown in the photo below. Try it and see if doing a reset in EV mode gives you 999 MTE (based on 99.9 MPG). ( $1oo says it won't )

The only thing wrong with Bill Whiney's posts is he stated in an earlier post:

"Bottom line: the moving mpg average & therefore miles to empty changes only very slowly."

WRONG. The MTE changes based on tank level. MPG does not.

MPG is based on rate of fuel used. Wheather you have 1 gallon in your tank or 17 gallons in your tank, your miles per gallon does not change.

If your fuel MPG goes up because you are going downhill, but you have a hole in your tank and are dropping fuel on the ground, your MTE can go DOWN while MPG goes up. Bill could not separate these two concepts in his mind.

 

What I hear you saying is that the MTE is based on the amount of fuel in the tank? That is not very accurately measured, or at least I know of no accurate measure available. The only way the trip computer could know the fuel level is to measure the fuel flow to the engine (providing an estimated tank level based on fuel used), is that what you mean?

But it must be using an estimated MPG somehow, in order to know how far whatever is left in the tank will take you... [Fuel remaining] X MPG (i.e. fuel use rate) = MTE, correct?

Like Bill, I also had thought that MTE was based on fuel flow measurements vs miles driven, and based a moving average MPG to determine how many miles were left in the tank.

Where did you get your information?