Number of miles travelled and remaining miles until empty count is way off

[Reidog]

I noticed something strange today. I filled up the gas tank and rest the Trip A mileage. The mileage range said I had 310 miles to empty. It now says I went 135 miles have 175 miles. I did not drive any where near 135 miles! I calculated and at most, I drove maybe 75-80 miles today. Has anyone else experienced this? Is it something that I need to worry about?

 

[Proyota]

Are you saying you drove 75 miles but the trip odometer says you drove 135

 

[Reidog]

Yes. That’s a significant difference in mileage, which is why I’m wondering if it’s something I should get checked out.

 

[Tripod1404]

It is normal. Distance to empty calculations come with “worst case scenario” from the factory and slowly update as the car’s computer get more data on your driving habits.

It goes down faster than the actual miles driven because the computer tries to estimate the remaining distance, but assumes you will get something like 15 MPG. Like if you have a full tank, it will calculate range as 15x18=270 miles. Let say you drive until a gallon of fuel is consumed. The computer will now calculate the range as 15x17=255. But in reality, If you are actually getting 25 MPG you initial range was 18x25=450 and traveled 15 miles, which will only consume 0.6 gallons of fuel at 25 MPG.

So in short, the computer over estimates the fuel that will be used in the future, which causes the distance to empty to go down faster than the actual miles traveled.

 

[Reidog]

But would this account for the trip A counter saying I went 135 miles? I swear I’m not high, there is no way I went that many miles.

Maybe on my next fill up I will have to rest everything and see if it doesn’t again. Maybe it’s just some weird computer glitch.

 

[ferrari1898]

I have noticed my Land Cruiser's Range to be more of a guess than estimate. We do tow with our Toyota, which does not help (our previous Honda was always way off due to past driving history while toying pushing the average down).

IF you are saying you drove 80 miles and the odometer says you drove 135, that would be something to discuss with the dealer. Even with aftermarket tires, I would find that to be hard to explain.

Also to avoid a trip to the dealer, I would also map out a 25 mile loop on Google Maps and see how far off things really are.

 

[pandaExpress]

While we're on this topic, my low fuel warning light goes on with about 17 miles left on the distance to empty (DTE) display. I've taken it down to 3 or 4 miles remaining before filling up. In that instance I had traveled 364 miles and it took 15.26 gallons to refill. The tank capacity is 17.9 gallons. I'm sure that isn't all usable, but I bet at least another gallon is available. How far past 0.0 DTE have you gone, and what's the most fuel you've been able to put in the tank? I try to fill up at Costco, where premium fuel is much less expensive than elsewhere, but that isn't always convenient.

 

[ferrari1898]

I have only added 15.527 and our DTE was still 20-ish. I have yet to run it down to 0 miles left, but I suspect there is 20-30 miles left after it is on 0. The previous Honda was 20 and pretty close to bone dry by my math. My Subaru meant business. When it said 0, it meant it. I missed an exit and 4 miles to the next exit I was misfiring.

 

[solidbrix]

I got mine down to "2 miles left" (started at 294 miles) during a roadtrip and when I filled it at the pump: 15.3 gallons of gas (tank is 17.9). So you can easily go another 20-30 miles after you hit 0.

 

[pandaExpress]

I admit I'm compulsive about keeping fuel records for vehicles I own. That said, here's a chart showing indicated distance to empty vs. remaining fuel in the tank (17.9 gallons nominal capacity minus the amount added to the tank at refilling) for each tank I've purchased since I got the 1958 edition in early July. There's a good statistical relationship between these two numbers. This suggests that for my vehicle (yours might differ), I would have 2.1 gallons remaining when DTE gets to 0. I don't know how far one could push it beyond that, but it sure seems that you could go at least 20 miles past 0.0 (nominally about one gallon left in the tank) without worrying too much about running out of fuel. Anybody tried to push it, or (hopefully not) actually run out of fuel? If so, it would be interesting to know what the DTE indicated, and how much fuel it took to fill it up so we would know what the usable tank volume is.

 

[LCMud]

I admit I'm compulsive about keeping fuel records for vehicles I own. That said, here's a chart showing indicated distance to empty vs. remaining fuel in the tank (17.9 gallons nominal capacity minus the amount added to the tank at refilling) for each tank I've purchased since I got the 1958 edition in early July. There's a good statistical relationship between these two numbers. This suggests that for my vehicle (yours might differ), I would have 2.1 gallons remaining when DTE gets to 0. I don't know how far one could push it beyond that, but it sure seems that you could go at least 20 miles past 0.0 (nominally about one gallon left in the tank) without worrying too much about running out of fuel. Anybody tried to push it, or (hopefully not) actually run out of fuel? If so, it would be interesting to know what the DTE indicated, and how much fuel it took to fill it up so we would know what the usable tank volume is.

Nice. Is it true your driving was similar for all the data points so that the reference MPG used by the car to calculate miles remaining is not changing much? I assume you would not get a linear relationship if this wasn’t the case and also the variance away from linear you could track back to how you drove for that data point.

 

[LCMud]

While we're on this topic, my low fuel warning light goes on with about 17 miles left on the distance to empty (DTE) display. I've taken it down to 3 or 4 miles remaining before filling up. In that instance I had traveled 364 miles and it took 15.26 gallons to refill. The tank capacity is 17.9 gallons. I'm sure that isn't all usable, but I bet at least another gallon is available. How far past 0.0 DTE have you gone, and what's the most fuel you've been able to put in the tank? I try to fill up at Costco, where premium fuel is much less expensive than elsewhere, but that isn't always convenient.

So that is 23.85 MPG, a good number. Best I’ve seen is 22.8 MPG but I’ve only got 1050 miles on the LC.

 

[pandaExpress]

So that is 23.85 MPG, a good number. Best I’ve seen is 22.8 MPG but I’ve only got 1050 miles on the LC.

Mine has ranged from 22.8 to 23.9 for the seven refills, a pretty consistent average. There have been no long road trips or significant off-road adventures yet; most all of that is a 28-mile commute.

 

[ultane]

While we're on this topic, my low fuel warning light goes on with about 17 miles left on the distance to empty (DTE) display. I've taken it down to 3 or 4 miles remaining before filling up. In that instance I had traveled 364 miles and it took 15.26 gallons to refill. The tank capacity is 17.9 gallons. I'm sure that isn't all usable, but I bet at least another gallon is available. How far past 0.0 DTE have you gone, and what's the most fuel you've been able to put in the tank? I try to fill up at Costco, where premium fuel is much less expensive than elsewhere, but that isn't always convenient.

On the day of purchase, I wanted to get as much E10 out of the tank as possible. So I just kept driving after 0.0, so that I could fill with E0 fuel. I finally put 16.9 - 17 gallons of E0 fuel in Miss Daisy. I have done that several times since, further diluting the ethanol remaining in the tank with 93 octane E0 fuel.. I still have those receipts. Miss Daisy stays parked in NC until I can finalize my move up there from Florida. Once there, I will be able to use E10 fuel without worry of phase separation occurring.

 

[b407driver]

Nice. Is it true your driving was similar for all the data points so that the reference MPG used by the car to calculate miles remaining is not changing much? I assume you would not get a linear relationship if this wasn’t the case and also the variance away from linear you could track back to how you drove for that data point.

That's exactly why I set Trip A to show Distance and Avg MPH, which gives me an idea of how much city/offroad vs freeway driving I did (approximately). I used to track time in the 4Runner so that I could calculate this.