Miles until next fuel up... inaccurate?

I work off 10 gallons.

I take my tank mileage, deduct 3 for a generous error and multiply by 10 to get my fill-up distance and compare it to my trip A (which I reset after each fill-up. If I can't do a whole trip I'll fill up before it, otherwise I'll fill up after. Distance to go is pretty conservative so I don't pay it too much heed any more.

 

Miles until your next fill-up is always going to be inaccurate....cause the G3 never knows when you're going to fill up again.
DTE is also inaccurate.
When the last bar ('pip' is what the hipsters call it) starts to flash, you have approximately 1.8 gallons of fuel remaining. Take THAT for what it's worth.

YMMV...

 

I think the DTE takes the data from previous tank into its equation. My first few tanks on the Prius were between 570-590miles to empty. After I converted it to plugin that DTE started climbing every tank. It started with 717 miles. My current tank shows 838 miles to empty after fill up. I'm expecting to drive at least 1100 miles on this tank.
Also from the first pip blink to 0DTE is inaccurate too. The last pip start flashing at around 23-28 miles DTE. From that point to 0DTE is only about 15-20 miles. Once you've reached 0 miles to empty, you can at least drive 50 miles before fill up and still have at least 1 gallon in the tank. I've driven 200 miles with the last pip flashing before filling. According to the amount of gas I've pumped, I could have driven another 50 more miles. Bob Wilson did a test where he drove over 100 miles on 0DTE before he ran out of gas.

 

By necessity, Distance To Empty has a large safety margin built in. Because fuel use varies enormously by conditions (driver style, traffic, speed, weather, elevation change, warmup cycles, AC use, ethanol and energy content, etc.), and all sensors have some measurement error, the display cannot be as accurate as many of us desire. And the more accurate it gets, the more drivers end up stranded on the wrong side of the error curve, causing considerable problems for the manufacturer's complaint and PR departments.

If you want to run lower on the fuel gauge, first, go all the way to DTE = 0 miles. Then use a ScanGauge, programmed to show the tank fuel level (Flv on Adrian's spreadsheet) to run down a bit more. Mine reads about 1.5 gallons at DTE=0, then continues falling until reaching a floor of 0.7 gallons.

Then you are on your own, calculating the bottom as best you can. And if you screw up by running dry, it isn't anyone else's fault, as the warning flags were blaring quite a ways back.

Be sure to read Bob Wilson's thread about testing the actual bottom of the tank.

Also remember that most of the distances past the blinking pip or DTE=0 that people estimate here typical numbers, not absolutes. Individual cars will vary, and a few owners must get the unlucky short straws. I seem to remember one Gen3 reader (not Jimbo with his Gen2) running dry just 7 miles after noticing DTE = 0.

 

Fuzzy1, do you have enough experience with Flv on your car to comment on it's accuracy at points other than DTE=0? What does it read after a careful fillup?

How fast does it vary as the gas sloshes around in the tank in corners, braking and acceleration? IIRC it says quick update or something like that on the sensor list.

 

My fillups, stopping at first or second click, generally produce Flv = 11.0 - 11.2. The top two pips on my gauge on rotten, but from 7 pips on down, the dash gauge and ScanGauge track each other fairly well.

Flv displays considerable slosh, so the driver must mentally filter and average the readings. When Flv reads 0.7 with no more sloshing, the tank is very low.