Distance To EMPTY readout after REFUELLING

The DTE is a bit all over the place. I don't rely on it at all. Like with gen3.
I have noted down the DTE and TripA consumption values for several tanks and will post results sooner or later.

 

My suspicion is that it registered the additional fuel as a full refuel and calculated an abnormally high mpg and displayed this as a reduced DTE. Once you had driven around for a while it was able to recalculate your mileage and revised the DTE accordingly. So you see, it's still being smart. Just a tad slower than usual!

 

Mine does the same thing, Alan. The DTE is never consistent.
And since the weather has cooled off, my MPG is all over the map. Now I just always refuel when I reach 1/2 tank, or 1/4 tank, and go on my Merry way.

 

It is not smart since it knows how many miles & how many gallons. It is a (non-life threatening) software bug!
I have been told that DTE was unreliable. I fill up before empty and, now you mention it, I have been perplexed by the lower DTE number.
This bug has been around since at least Gen 3.

Moral of the story: Ignore DTE.

 

I've had DTE in several different cars now and they all work roughly the same way. By that, I mean they constantly assess your driving style and the current and recent roads and ASSUME you will not vary in any way in future. That is their instant DTE which will seldom, if ever be reliable!

As soon as the roads are faster/slower, or steeper, or yet stop-go/continuous driving DTE will change fairly swiftly, which may have adverse consequences of you ever great it as reliable. It's simply a snapshot of your recent driving history, but not a prediction of what's to come.

Hope that explains it's practical unreliability, or even helps you get to sleep, CC.

 

While I agree that is how it should work, it appears that the DTE assumes you are filling up the tank from empty. Some of us refill when the level is 1/4 or 1/2, making the DTE calculation useless.

 

That's exactly what I maintain, it's useless!

 

Thanks RCO. Very good explanation.

 

This thread is a good reminder. I'm not sure what to believe when looking at all the Prius MPG numbers. I think some owners rely on those displays way too much.

- Depending on when I refill, my DTE number varies quite a bit.
- The From-the-Flag number will sometimes jump around oddly.
- Depending on when I refill, the trip-A MPG number can vary by as much as 8 MPG, high or low, from tank to tank.

To be honest, I'm not sure what to believe. (And the short trip MPG numbers are meaningless.) The only accurate way to check gas mileage is to hand calculate it: The number of miles driven -- divided by the number of gallons purchased.

The trip-A MPG numbers seem to be fairly accurate... But several times my trip-A display indicated I was getting 58 MPG. But after refueling and doing the calculation, it was really only 51 or 52 MPG. That's a big difference. That's why I don't take any chances. I usually do not let the gas guage go below 1/4 remaining.

 

I have the Automatic ODBII dongle, which provides granular data. Overall, the data generated is pretty consistent with what the Prius reports. I assume they are pulling from the same dataset. On the other hand, the Prius predictions, as stated, are not very reliable.

 

My 52 full tank Prius-reporting numbers are somewhat erratic, but fall within a predictable range of 3 to 6 percent overstated as compared to hand calculated. Only once in the car's lifetime has the MPG not been overstated by the computer. My 4.8 percent delta average has not changed beyond +/- .3 since I established a baseline after the fourth tank.