Distance to Empty consistently innacurate

[kern417]

So I've had my E70 for a few months now and I have noticed a bizarre trend. Every time I fill up my tank, it reports ~430 miles to empty. This plummets as I drive the car, and by the time it says 50 miles to empty I have only driven ~300 miles. This happens every. single. time.

The only thing I have noticed is that 2 of the belly pans are missing under the engine/subframe. I'm not sure why or how (I bought the car used, whatever), but I bought replacements. I still don't see how this would affect the car's estimated mpg not adapting after this long.

Thoughts?

[RichardR0404]

Range is usually just a reference and with my daily wide open throttle driving it never worked... my best suggestion is count how many miles you can go on a quater tank and use that asba reference

[RichardR0404]

with my diesel the best i can do is 450km /
280 miles per tank....

[do_0b]

Yeah mines like that. When i drive on on the freeway it goes up lol.

[kern417]

Ok I wasn't sure if it was normal or not. I've never had a car be that persistent that it could get 75+ miles to a tank more than it has, as far as I know, ever gotten. All I do is reset the trip mileage every time I fill up and watch that, but weird that it can't seem to calibrate itself. And of course, the long term mpg always says 17+mpg when 350 miles to a tank is closer to 15. Now it feels like the 3.0si wasn't even worth it, but I guess that's just the drawback of a large suv. Next time I'll just get the V8 so I can enjoy it at least haha.

[RobDawson]

That sounds really low for a tank. I have the 3.0d but use it entirely on country/urban roads and get 500 ish to a tank (or would if it didn't get iffy at the quarter tank mark). After a reset the estimated mpg climbs slowely to around 27miles per gallon. Are you sure you haven't got a leak?

[Colodano]

Mine does the same thing, I just know that I am generally needing to fill at around 300 per tank, and I always reset trip odo. when I fill up. Maybe doing a long freeway drive, all downhill, with a tailwind the whole time it could get closer to 400 haha.

[kern417]

So I forgot to upgrade this thread, but I did a few things to try and improve fuel economy.

I remembered that I did a vehicle inspection at BMW after purchasing the car, and they found several underbody panels were missing. I realized that could be affecting fuel economy. So I bought all of them used on ebay and installed them. I've seen a slight gain but haven't gone through a whole tank to really see if there's a difference. I'm not sure why the previous owner removed them, but I think they'll be very helpful for smoothing air going under the car and reducing drag. I still need a few more fasteners to complete everything but they're on order now. We'll see how the mileage looks after going through a few tanks.

[M5_1of400]

Originally Posted by RichardR0404

with my diesel the best i can do is 450km /
280 miles per tank....

That's crazy low for a 35d... I usually get 500-550 miles and about 600-650 on long trip.

If I were you I would take a look at the maintenance of your engine to see what is going on there.

[Qsilver7]

Dont' forget to take topography (lots of hills (Cincy) vs mostly flat land (Houston), the type of traffic/road conditions being driven. Perhpas the AVG MPH should be listed along with the AVG MPG because this would give another indication of why the avg MPG may be higher or lower.

A lower avg MPH will have a lower avg MPG and vice versa. If you are only getting 28 MPH on average vs someone that is getting 35 MPH on average...the latter will also have a higher avg MPG. It may also be due to longer idle times in urban traffic vs someone driving on well timed interstate and long boulevard/parkways with timed lights.

[kern417]

Originally Posted by Qsilver7

Dont' forget to take topography (lots of hills (Cincy) vs mostly flat land (Houston), the type of traffic/road conditions being driven. Perhpas the AVG MPH should be listed along with the AVG MPG because this would give another indication of why the avg MPG may be higher or lower.

A lower avg MPH will have a lower avg MPG and vice versa. If you are only getting 28 MPH on average vs someone that is getting 35 MPH on average...the latter will also have a higher avg MPG. It may also be due to longer idle times in urban traffic vs someone driving on well timed interstate and long boulevard/parkways with timed lights.

True. My new job has the shortest commute I've had in years among other things having an effect on it, but I just expected it to be more of a gas sipper. This weekend I'm making a 600 mile trip so it'll really be put to the highway mileage test.

[Qsilver7]

Originally Posted by kern417

...This weekend I'm making a 600 mile trip so it'll really be put to the highway mileage test.

Ah yes...I love long road trips when you get to travel at consistent speeds with little braking. Please do post back what your highway avg MPG was on this trip...it will be interesting to see the difference.

[M5_1of400]

Originally Posted by kern417

True. My new job has the shortest commute I've had in years among other things having an effect on it, but I just expected it to be more of a gas sipper. This weekend I'm making a 600 mile trip so it'll really be put to the highway mileage test.

Yes, there are multiple things that can affect MPGs but that is a huge difference.. unless OP is permanently towing a 10000 lb boat and his work location is at the top of a mountain I just don't see how MPGs can be affected that much.

Your 600 mile trip will be a good way to test and see.

[X5 MAN]

Originally Posted by DieselDemonDM

Yes, there are multiple things that can affect MPGs but that is a huge difference.. unless OP is permanently towing a 10000 lb boat and his work location is at the top of a mountain I just don't see how MPGs can be affected that much.

Your 600 mile trip will be a good way to test and see.

When you are driving on a hilly terrain, the downward part of the drive generally negates the higher MPG used during upward climb., unless you are heavy footed and don't use coasting while going downhill

[bandwagn]

City driving is a mpg killer - especially with stoplights, traffic & such

[do_0b]

Originally Posted by bandwagn

City driving is a mpg killer - especially with stoplights, traffic & such

+1 city driving i get 350km (217 miles) a tank and freeway i get about an extra 150km (93 miles)

[yco]

that range is being constantly being calculated by the car according to speed, driving style.. basically how far you travel with how much fuel.. thats the reason kern..

[M5_1of400]

Originally Posted by do_0b

+1 city driving i get 350km (217 miles) a tank and freeway i get about an extra 150km (93 miles)

well.. you also have a monster X5M.. there is a slight difference between your engine an the 35d engine.. lol

[do_0b]

Originally Posted by DieselDemonDM

well.. you also have a monster X5M.. there is a slight difference between your engine an the 35d engine.. lol

hahaha
just saying...city driving kills the gassss

[M5_1of400]

Originally Posted by do_0b

hahaha
just saying...city driving kills the gassss

agree 100% on my 35d I get on average 25-26 MPG.. that's about 60% highway 40% city.. and trust me.. here in Houston there is a lot of stop and go traffic.. even on the highway.. I still squeeze a good 500 miles per tank.

Long distance trips cruising at 70-75 MPH with little to no stopping gives me about 600-650 miles... somewhere I read somebody getting close to 700 on a single tank.. had to be under the absolute perfect ideal conditions and running on fumes at the end.

BTW.. I made a mistake, seem like to have a monster X6M not a 5 .. yes.. I'm jealous!!

[RichardR0404]

Originally Posted by DieselDemonDM

That's crazy low for a 35d... I usually get 500-550 miles and about 600-650 on long trip.

If I were you I would take a look at the maintenance of your engine to see what is going on there.

There isn’t anything to do with my maintenance. It’s been over done. I get same mileage from my old motor with has more tha 50k hours on it and this motor that only has 35k km on it after the original one blew. Back in 2012 when I was 16 I can’t afford a X5M so I have to use all my oil field earned cash to finance a 35d, which is a very rare one since it has 3rd row seat and cooled seat, basically every single option is ticked except M sport cause it looks stupid back then. I have been driving it like a X5M, running through a set of tire in like 60 months, go to track day destroying Honda civics, delivering equipment and stuff for oil field and leave the car running for more than 2 weeks because 35d won’t start back up in -45C weather. I made it from Calgary to Montréal in 30hours so now you kinda know how I drive my 35d, more like a M3 than a X5..... I am trading it in for a Cayenne turbo S or potentially a X7M or a M760Li, my car USB sitting in my garage till it’s get traded, taking my 89’ town car as a daily now. I will post my vin then you guys know don’t buy this VIN

[kern417]

So I think the trip went well. Granted I had the family + trunk full of luggage, but both ways I got upwards of 18-19mpg. That's a lot better than the 15 I was making, and the mountains in tennessee/north georgia killed my mileage fast. I think I could get 20+ if the roads stayed flat, or even with the highway traffic on my normal commute when it's only me in the car.

It still doesn't fix the gauge inaccuracy though. One time I filled up and it estimated 480 miles to empty that would be amazing, but I got nowhere close lol. I also replaced the battery before the trip which I believe reset all the running calculations.