Very Inaccurate Fuel Range

[board57796]

Since I’ve bought the car a couple years ago, my indicated range after a fill-up will show around 400 miles, but I’m always pulling into a gas station to refill about 230-250 miles later. Is it just me, or are other people’s cars extremely optimistic on their range? I drive almost the same routes and style every week, and it never “adapts” to that.

[Opie55]

That is weird, and I'm in the same city so my experience is "altitude controlled." I drive mostly around town, so mine will usually say right around 300 and often slightly less - like 290. The only way mine ever says 400 is if I have done a significant road trip on the prior tank. And to get that high it would have to be more than going to the Springs and back. I'd have to go to Trinidad or something.

[Opie55]

Another question for you is if you fill up after doing your typical around town routine, then jump on the the highway, what happens to the 400 number? If I fill up before a road trip and it says 290 or so, then get on the highway, that number goes up for a long time before it finally starts to drop as the computer recalculates. On 25 south I can go to at least Pueblo - probably Walsenburg - before the number starts to drop again.

[board57796]

Yeah I know what you mean about the range bumping up after a long road trip. My E38 750iL does that and is much more adaptive to range versus driving conditions. I can cruise down from Grand Junction in that thing and fill up and the range will say close to 600 miles, and it will actually achieve that it I keep cruising. But the F06 seems to always, whether I fill up during my regular city week, or after a road trip, will show 390-410 miles of range and I always end up getting a low fuel light around 220 miles almost regardless of city/highway. The range just seems to drop linearly by 1 mile for every .6-.7 miles of actual driving, I’d say.

Another odd thing about my range is the little range curved “bar graph” graphic under the tach will sometimes not “fill in” all the way, even though the actual fuel gauge shows a full tank. It shows like 95% filled in sometimes, other times it’s completely filled in. This happens even if I top off the tank at the pump.

[Opie55]

Yeah, the bar graph below the tach should not fill in I don't think unless it's telling you the 600 mile range or so. When mine say 300 it's only maybe 2/3 of the way across.

But your statement that you get about 220 actual miles before fill up regardless of city or highway driving is odd and makes me wonder if you have an underlying issue. You said you drive mostly the same routine, but you did not say what that routine was. As for me, I can easily go a tank of gas without ever getting on a highway because I live near the zoo. But if you drive C470 or even Santa Fe every day as part of your commute, then your 400 number is less surprising. But to see where the correlation has gone wrong I'd need to know what your actual mpg is. What does your trip computer say your mpg is after a tank of this routine drive? What does calculating it the old-fashioned way say it is? Because I drive so much in town, my overall average mpg is only about 14.5. But it definitely matters if it's city or highway. With a just a few short highway trips just across town it can go to 20 mpg.

[iamvanja]

Mine is also super optimistic 400-450 after filling up the tank.
Actual range is closer to 300-330 miles.

[board57796]

Originally Posted by Opie55

Yeah, the bar graph below the tach should not fill in I don't think unless it's telling you the 600 mile range or so. When mine say 300 it's only maybe 2/3 of the way across.

But your statement that you get about 220 actual miles before fill up regardless of city or highway driving is odd and makes me wonder if you have an underlying issue. You said you drive mostly the same routine, but you did not say what that routine was. As for me, I can easily go a tank of gas without ever getting on a highway because I live near the zoo. But if you drive C470 or even Santa Fe every day as part of your commute, then your 400 number is less surprising. But to see where the correlation has gone wrong I'd need to know what your actual mpg is. What does your trip computer say your mpg is after a tank of this routine drive? What does calculating it the old-fashioned way say it is? Because I drive so much in town, my overall average mpg is only about 14.5. But it definitely matters if it's city or highway. With a just a few short highway trips just across town it can go to 20 mpg.

Interesting about the bar graph gauge.

I’m at 104th and Tower area and work at DEN (aka DIA) so only about 10 miles with just a few stop lights. Other than that I mostly am around my house doing errands, etc. I did recently have what I think is a spark plug or coil issue causing a misfire after the BM3 tune so maybe once I replace those the mileage will go up. Granted I do “drive it like I stole it” quite often so there’s that. I just figured the “predicted range” would have adjusted to that driving style by now and not always shoot up to around 400 miles on a full tank.

[Qsilver7]

One calculation not mentioned is the AVG MPH. What is the average MPH for each tank? That will help bring some (or another) important fact to the table. If the average MPH is lower...then even with some highway driving...a lower MPH average means that at some point city/urban driving or some stop/start driving is causing the fuel consumption to increase.

If you are getting more miles out of a tank of gas...more than likely your average MPH is going to be higher, as well...in comparison to those that are getting less miles out of a tank of gas.

For example, if I do a trip that is mostly highway and can average 45 MPH to 65 MPH...I've always gotten more miles out of a tank of gas...with the average MPG usually being between 20 MPG-24 MPG. But as soon as I go back to more city/urban or stop-n-go driving...not only does the average MPH go down to around 20 MPH...but my average MPG also goes down, too and usually averages between 14 MPG - 18 MPG.

One more thought...what driving mode is being used? Take note of the tachometer...when using SPORT or SPORT+ versus when using COMFORT or COMFORT+. When using the latter two driving modes...the tachometer tends to stay around 1k....but when using one of the two sport modes...the tack revs higher...which will also mean more fuel consumption.