midnightsun

Hello guys

Got my M5T 2 months ago, so I'm still in the learning mode on its behaviours. Took the car to the Spa 24hrs this weekend with a planned detour thru Germany on the way home, with the intention to let it rip (legally) as soon as we hit the Autobahn heavens of Greater Germany. Unexpectedly the detour also provided me with some intresting data on itsFuel economy

We left Spa at 03:00hrs... a bit low on gas, but not to worry, according to the boardcomputer there was enough fuel for at least another 50km. Surely there would be a gas station open between Spa and the Belgium/German border.
Cruising along at a steady 160kph the " fuel range" remained steady at 48km which was interesting considering we had already covered more than 40km!

As we crossed the border...still no gas station... by now the range finally started to wind down, but as it indicated that it still had enough gas for another 40km, I was not extremely worried....although I did ease of the throttle a bit. After another 20km I was getting seriously pissed off, here I was on this beautifull piece of open and totally deserted German highway doing an economy run at 120kmph!

When the computer stated that at the current consumption level it could cover 36km there was a road sign...indicating that the next gas station was....51km down the road!!!!!
To indicate the urgency of the fuel situation the reserve light come on. Now I was getting worried.....seriously worried indeed!!!
Trying to somehow make up for the missing 20km my foot came of the throttle but even at 100kmph the range kept winding down until it reached 15km and then.... no indication at all.
:

Time for some quick calculations...
I flipped the boardcomp from range to milage and it showed 9L for 100km, meaning 11km to the litre, meaning there was something like 1,5L left in the tank...... and we had at least another 20 km to go....f**k!!!!

Barely touching the accelerator the fuel consumption goes down to 7,5L/100km...as we hit 80kmph. Will 13km to the litre be enough?! Nightmare visions of doing another 6km hike in 24hrs (a walk around the Spa circuit = 6,7km) enter my mind as the road starts to climb...S**t!!! Consumption rises to 8,5!!!

Then finally..in the distance.. a light!!!! Yes!!! its the Gas station!!! But why the f**k did they build it at the top of the hill !! To my relief, no sputters or coughs, we roll into the station, according to the day counter we've covered 110km since leaving Spa!!!!

As a reward I fill her up with 100 octane Ultimate, taking 88,6 litres to top her off!!!

As we leave the station I finally floor the pedal, show me what you got baby!!!! The odometer finally stops at a hover on 260kmph, I quickly reset the average speed and get 254kmph.
I flipp the comp one more time to check the Fuel consumption...
33L for 100km, now that's more like it

Simonal

Hi your not the first to comment on the "reliablilty" of the fuel gauge! Many times board members have driven their cars apparently on air with the range meter on the computer reading no range and the fuel gauage at the other end of the reserve section, happened to me the a while ago when coming back home, did not want to fill up on the motoway as it is more expensive in the uk on motoways.

Got home still on the reserve and then drove somewhere else around 15-20 km more on an "empty" tank.

BTW used to live in your town for around a year great fun

farrell

The fuel consumption & distance to empty function on the HAL9000 OBC is so far out, its beyond belief.

For quite some time I thought I was seeing 25-27 mpg @ 75-80 mph.
Then, as fuel started rising in price steadily in UK again, I decided to check a few tank fulls from full to the warning light.
Reality was 23-24 mpg absolute max.

In mixed driving with cold starts, some Country B roads & A road dual carriageways I am actually getting no more than 20 mpg.

Obviously this is only my car & driving styles do differ.

Imho the fuel consumption aspect of the OBC is only useful as a psychological aid. Now I know the truth, It only enforces the drive it 3 days out of 7 max that I am struggling to keep to.

Cheers
Farrell

Mmm-Five

I get about 60 miles out of the tank once the reserve light comes on. Lowest MPG was 6mpg on the track, and highest was 32mpg through 10 miles of roadworks on the motorway @ 50mph. I do notice fuel 'economy' dropping off drastically when the clearances need doing, to a max of 20mpg no matter how I drive. I regularly get 400 miles per fill, which equates to an average of over 20mpg as I try to fill up as soon as the reserve light comes on and usually can't get more than about 82 litres in.

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2006 e86 Z4MC (überkart)
1990 e34 536i (ex-überbarge-zwei)
1994 e34 538i (ex-überbarge-eins)
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vadas1

When my computer fuel gauge says no miles left I know ( give or take a litre ) that I have 20 litres left in the tank. I could reset the computer but it doesn't seem worth it.



ralph (vadas1)

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* If it ain't broke fix it till it is *

Jahangeer

------------

My computer once told me I had 35km left, the night before I, then the next morning the car would not start, I had to use the reserve fuel in the boot.

Was the computer thrown out by the 18 wheels I had or the new schrick camshafts?

I hear one can recalibrate the fuel consumption readings on the onboard computer.

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Regards
J

vadas1

That's right you can. There are a number of previous posts on M5board that explain how.



ralph (vadas1)

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* If it ain't broke fix it till it is *

MBrasil

Mine usualy shows 15.5 L/100km, and on real world no more than 450 km until the warning light comes on. Is this normal, or am I being robbed by my drunk M5 ???

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Audi = DKW
Mercedes = Taxi or truck
Porsches = has all my respect
BMW = rocks

Phlem5

When the fuel level is getting low (too often for my pocket) I put my obc to 'test07' to find out how many litres are left in the tank, it does seem to stick at 7 when the low fuel light comes on. One time it was reading 4l in tank and I had parked at the side of a cambered road i.e. leaning to the left and the engine conked out, I managed to get it restarted on the level - so @ 4l get to the petrol station fast. I reckon I get about 24mpg on average.
Cheers.

MBrasil

How does the test thing works on E34 M5. I just know how to use it on M3 E36.

Anyone ???

__________________
Audi = DKW
Mercedes = Taxi or truck
Porsches = has all my respect
BMW = rocks