Distance to Empty calculation

[himemsys]

On cars that have a "distance to empty" calculation, how does your car calculate?

On our 2018 CRV, it starts off with a mileage that is based on recent driving. For example, after a fill-up of mostly highway driving, the distance to empty will start off around 350 miles. After a fill-up of mostly city driving, it will start off closer to 300 miles. Here's the interesting part, though. As you drive, it will NEVER increase the distance to empty calculation! If you end up driving a bunch of highway miles, it will just slow down the distance to empty value.

On our 2013 Volvo S80, the distance to empty value will actually INCREASE if you start driving a bunch of highway miles. So, it may start off at 300 miles, but within 10 miles of mostly highway miles, the distance to empty value will JUMP up to 350 or even 400 miles.

The CRV will NEVER increase its distance to empty. It will only slow down the drop of the already existing distance to empty value. So, if it starts off at 300 miles, and I start a long highway run, it will stay at 300 miles for many miles, and start slowly trickling down the distance to empty from there.

How does your car handle this calculation?

 

[SC Maintenance]

Our 2019 Rav 4 uses the total average mileage as its base.

The DTE never increases - but its decrease will slow. For example if I am on the highway and it says 200 miles, in 100 miles it may show now 120 DTE because highway mileage it is better than average, for example.

When it gets to zero I still have 2.25 gallons per Toyota. It seems to match my experience when filling from zero.

 

[supton]

Not sure… I do mostly highway and still look at the gas gauge, most of the time. When range gets below 100 miles I decide when I’ll fill up. It might adjust as it goes along, but for the first 300 or so miles I don’t pay attention to range left, so I’d miss it if it did adjust.

 

[vavavroom]

Current consumption is dithered and correlated to the remaining amount of fuel. The remaining distance may temporarily increase in the short term while obviously decreasing in the long run.

 

[fdcg27]

The HAH does exactly that. It never increases range remaining but range remaining may sit steady as miles run from fillup increase.
Actually, it did increase range remaining once, in the first spring in which I owned it. The weather had turned warm and it recalculated range remaining in a whirl of digits on the display. Never saw that again.

 

[eljefino]

My wife's HHR used to stop the estimate with about 75 miles remaining. Foolish car, that's when I really wanted to know!

Obligatory:

 

[dishdude]

My wife's HHR used to stop the estimate with about 75 miles remaining. Foolish car, that's when I really wanted to know!

Smart, actually. That's when that estimate is the least accurate, if you change your driving style that 75 could be a lot less.

 

[John105]

We once drove a Toyota Sienna back from Toronto and the range was down to 9. I used logic and said I can go another 100 miles as I am clueless what it's basing that on, but it did bother me. It's math imho. We know how much fuel we put in and how far we've gone. Now the car can display the mpgs. range is irrelevant and obviously the car can't predict future driving, be it highway, city, bumper to bumper

 

[Hall]

My '08 G35 uses some unknown logic. My average MPG always settles down to around 19.5 and with ~20 gallons filled-up, you'd think it would show ~400 miles to empty but it never seems to go higher than 350-ish. As for the value it shows, it will increase the miles to empty if my driving is more open road/highway. My wife's Grand Highlander makes no sense whatsoever when it comes to DTE.

 

[Donald]

In the military it's called time to Bingo.

 

[dogememe]

If I take the highway home and go fast enough, the next morning the Bolt will have whatever estimated range number. Then if I take the local streets I can drive to work and end at work with a higher number than I left with. For example let’s say I leave work at 200 miles of range. Then I go fast on the highway (a 3 mile drive) I might use up 5 miles of range so I’ll get home with 195 miles of range. Then (assuming I don’t charge it) I start the morning with 195 miles of range. I can drive around town to work (3 miles) and get to work with 196 miles of range estimated.

Just goes to show how inaccurate these “miles to E” things are. The best, most accurate one was in my 2010 Escape. It was scary accurate. Of course, in a gas car, it mattered little.