Gas level miles mismatch

Just so you know, those things for miles remaining are always off. Even when you reach Zero, you usually have about 80 miles remaining in your tank (2 gallons)

 

I'm thinking of several ways that could happen, none of them particularly important. E.g. having added small amounts of fuel, leaving ignition on while refueling, steep hill climb when fuel is low, level sensor a bit out of calibration. And there just have to be more possibilities that I don't know about.

Don't over-think it. The "6 miles" DTE number isn't all that meaningful, it has a good bit of safety margin behind it, and there are ways to push the DTE number artificially low.

With 2 bars you ought have around 2 gallons left, or a bit more. Read the first post of this thread, though be ready for the possibility that your fuel gauging as drifted out of calibration, and possibly not in the direction of increased safety margin:
[WARNING] Running out of gas (Gen III) | PriusChat

 

Maybe just ignore the distance-to-empty gauge, rely on the gas gauge? And don't let it get too low.

 

Good plan! All the DTE gimmick accomplishes is confuse people who take it too seriously.

My owner's manual says there's 1.6 gallons left when the last gauge segment begins blinking. That's far more useful information, assuming it's a conservative estimate, which it probably is. (Someone measured and found there was actually 2.5 gallons left in his Prius.) From experience, I know that when the next-to-last segment goes off on my particular car, about half a gallon can be consumed before the last segment will beep and begin blinking.

 

What Mendel said. You have very little to lose, other than stress, by never ever looking at DTE. I do use it, out of curiosity and because it is there. But it is too easy to read more into it than it really means.

The fuel gauge bars show everything you need to know. Most bars represent about the same amount of fuel each. As CR94 just said, the bottom non-flashing bar means just half as much fuel as the bars above it. Then when the gauge beeps and the bottom bar starts flashing, you have somewhere in the range of 1.6 to 2.5 gallons remaining. DTE will quickly drop to 0, but in an urban area with lots of filling stations, no sweat, the car will go a fair distance after DTE first reads 0. But if you are out in the boonies and see these signs, TURN BACK!, return to the last fuel station(s):



As for adding fuel to just the half tank level, the only reason I ever do that is to get out of California or British Columbia to much cheaper fuel across the border in the next state or province.

 

I know in my gen too if everything is running generally correctly I will go about 480 MI and I'm starting to breathe fumes or the car is starting to run on fumes. Within 60 or so Miles I better be having a pump hanging out the side of my car but generally when I'm traveling and going somewhere I have a gallon or two of gas with me in an approved container in the back of the car.

 

Those miles remaining are calculated based on driving conditions...

Sometimes range are more and sometimes are less, and it usually calculated on a time/ distance everytime you drive it...

It is not a reliable tool to gauge available gasoline to empty tank....

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After you've been in a car like this a few months in my opinion one should know all this stuff but now that I have had another half for some time I can clearly see how some people just never be coming with much of anything so I understand how all this comes out to people with different types. It's really weird I could not imagine not being the way I am and being like my other half or my daughter I can't even imagine being so oblivious to stuff or things but a.

 

Even after a dozen years, I'm not good at predicting just how much fuel range I will lose when driving across the state into wet winter windstorms. Sometimes it loses just a little, but the one in April was bad enough to make me stop for refueling before crossing the mountain pass, just to make certain the car had some margin for sitting or rerouting in case of one of those frequent crash-induced blockages. In calm dry weather, or mild headwind and rain, it doesn't get low enough to be of concern.

 

I am not sure if the fuel gauge bars are more reliable or accurate. While my Prius seems fine, my Prius C doesn't. The fuel gauge sometimes stays long on 3 or 4 bars, then suddenly drops to 1 bar. Meanwhile the distance-to-empty meter looks more consistent.

 

The best way to judge it is to fill up, reset a trip meter. Drive 2-300 miles, fill up.
Divide the miles driven by the number of gallons. That is the most acurate way of
knowing your mpg.
If you average 45mpg, you can go abotu 500 on a tank of fuel. But, if you fill up at 2-250 miles,
you won't have to worry about running out of fuel... unless there is a leak..

 

I've been tracking the volume of fill ups (to full) versus the number of bars indicated on the gauge for some time now. Over the last 15 fill ups, this is what it looks like:

It indicates that the volume of fuel (in gal) I'll add to get the tank to full when the number of bars is x, is given simply by 10-x. Each bar therefore represents 1 gal of tank capacity, but since we know the tank holds 11.9 gal, the car must be squirreling away the last 1.9 gal, which should get me about 76 miles further at 40 mpg after the DTE crawls down to 0.

Assuming the 1 bar = 1 gal relation holds true, when the next-to-last segment has just gone off, there is 1bar (1 gal) + the reserve capacity (1.9 gal) = 2.9 gal remaining in the tank. According to @CR94's experience, ~0.5 gal after this (at 2.4 gal left), the last segment starts blinking.
This would corroborate the experience of the member that measured and found 2.5 gal left at that point.

 

How did you get zero bars? Mine starts at one blinking bar, and based on some experience watching odometers and DTE, I assign it a value of 0.5 bar. But that is the lowest it gets, never a true zero bars.

For some more detail and actual test results, read (just) the first post of this (too long) thread:

[WARNING] Running out of gas (Gen III) | PriusChat

 

I never did actually get to zero bars, but that last segment had been blinking for at least 12 miles and I rolled into a gas station about a half mile after the DTE went down to 0, so I assigned that event 0 bars. Had I assigned it 0.5 bars as you did, the equation would be even closer to y=10-x, with a marginally higher correlation coefficient.

 

Considering that my car usually goes roughly half as many miles on one solid bar, as it does on each of the next several bars up, I think the 0.5 assignment fits better. And when it first beeps to warn that the last bar just started blinking, DTE usually shows miles remaining consistent with about a half gallon.

I have gone more than a full gallon beyond DTE = 0 on a very few occaisions, though still well short of Bob's distances.

 

For one more data point:
When my last segment begins blinking, it takes 9.2 to 9.4 gallons to fill the tank until a typical pump snaps off. 11.9 gallons claimed capacity minus 9.4 = 2.5 gallons, the same as was measured. I would not recommend trying to take advantage of that entire 2.5, though!

 

My average is about 47mpg.
98% of the time I fill the tank when it gets to the half way mark. Mostly
because I'm driving 100 miles trips a few times a week and want to keep the tank as
full as possible. Because on the interstates there is always some idiot who refused to drive
respectfully and will case a wreck and block the road....

And at 47mpg, I know I can go at LEAST 500 miles on a tank of fuel. And I don't worry about
running out.

Only twice in the 4 years and 11 months I've owned this Prius have I gone down to the
flashing bar and still drove for a while, just to see how far and how much fuel it took to fill it up.
I think it was 10.2 gallons. But I did this close to a station so I didn't have far to go if it shut off.

 

I use the same approach. Pretty easy for me: filled up yesterday (was down to half on the gas gauge); two months to the day since the last fill up, lol.