E39 M5 - Fuel Consumption

[EDSEL1]

Just drove to the Loire and back in the M5 this weekend.
I had heard reports of around 24-25 MPG on the motorways etc..

I could could not get more than 18.6 ---- I put it on cruise control at around 80 MPH ---- drove quite frugally still not even 20 MPG...

Do I really have to drive around 70 for mid 20's consumption?

[Schermerhorn]

Lots of things contribute to fuel consumption

Weight

Tyre pressures

Air flow meter

How good a condition the engine is in (service)

Air con on/off

etc etc

[maddernj]

I did 1500 miles around Cornwall this summer and managed about 22mpg mixed. I saw 27.4 mpg on the motorway (M3 - A303 - A30) ave speed of about 75-80mph. Almost 380miles to a tank ! (it had just come back from its inspection II so i was hoping it would be sweet). And that was with me, wife and 10month old baby with all of her associated stuff (ie loads and loads).

Edited by maddernj on Tuesday 15th September 13:14

[Soovy]

Aircon means you lost about 6mpg.

[EDSEL1]

Air con was not on much --- checked the tyres before I left.
When I filled it up -- the range said 337 miles - only me and the bird and a morning suit in the car!

Only bought it about 2 weeks ago so this was the first long motorway stint....its a 1999 model

[Soovy]

It's an M5! It likes a drink!!

[M5Dave]

Soovy said:

It's an M5! It likes a drink!!

Not that much of a drink though.

According to the fuel computer, mine has averaged 21.5 mpg since I got it three years ago. Cruising at 80 on the motorway will see about 28 mpg.

[rassi]

My "historic" average over 70.000 km is 7.3 km/l (more or less 20.6 MPG) with about 80 % of this on motorway at 140-160 kph (87 - 100 mph), the rest city and A roads.

If I set the cruise at 80 mph I would get about 25.5 MPG

ETA: Aircon and lights always on, air pressure 2.4 bar in the fronts, 2.6 bar rears Michelin PS2

Edited by rassi on Tuesday 15th September 13:47

[EDSEL1]

maybe I am getting it wrong --- this could've been the whole trip including the a roads through the country.....the car did not come with a user manual --- still getting to grips with the functions etc...

[rassi]

EDSEL1 said:

maybe I am getting it wrong --- this could've been the whole trip including the a roads through the country.....the car did not come with a user manual --- still getting to grips with the functions etc...

For an owners manual, you can download it from here: http://www.m5board.com/vbulletin/m5-e39-e60-tips-t...

[TimR69]

70mph on the motorway = 30mpg.
Try it for more than about 5 minutes and it's impossible though

I reckon sensible driving on A, B roads and motorways will get around 24-25mpg but the more you use the performance the lower that will become.

[BillyB]

It would be worth calculating the mpg yourself based on actual fuel used and distance travelled as perhaps the OBC is calculating it wrong?

[E38]

Just did 1000miles to and around Ireland. 23mpg according to OBC. I believe it, but usually it is hopelessly optimistic... Work it out for yourself to be sure.

[rassi]

OBC can be adjusted to be very accurate - I set mine to read 3.6 % higher (1036 instead of 1000 in the OBC's Test 20), see here: http://kinmak.com/?page_id=14

E39 Instrument cluster test functions
Test functions

Menu Sub menu Sample Meaning
Test 1: Vehicle specific data 1.0 12345 VIN
1.1 4812 Body number
1.2 834762 Part number of cluster
1.3 010203 Coding/Diagnosis/Bus index
1.4 3495 Manufacturing data (calender week/year
1.5 04_600 Hardware/software number of cluster
1.6 415_06 Injection status, number of cylinders, engine factor
Test 2: Cluster system test Activates test for gauge drivers, indicators and LEDs
Test 3: SI data 3.0 1500 Litres
3.1 0 Periodic inspection days (not applicable for US)
Test 4: Fuel consumption data (current) 4.0 0267 26.7 litres/1000km
4.1 0073 7.3 litres/hour
Test 5: Fuel consumed/distance travelled 5.0 0195 19.5 litres/100km
5.1 226 Momentary distance to go (22km)
Test 6: Fuel level sensor input in litres 6.0 237415 Fuel level averaged.
LH sensor input = 23.7 litres - RH sensor input = 41.5 litres
6.1 0652 Total tank level averaged = 65.2 litres
1_6.2 0667 Indicated value and tank phase.
1 = Both sensors OK. 2 = One sensor fault.3 = implausible input
Test 7: Temperature and speed 7.0 032 Coolant temperature input 32C (90F)
7.1 245 Outside temperature input 24.5C (76F)
7.2 5283 Engine speed 5,283 RPM
7.3 085 Vehicle speed 58 km/h (36 mph)
Test 8: Input values in HEX code 8.0-8.3 XXX Hex code, instrument cluster inputs
Test 9: battery voltage 9.0 125 12.5 Volts
Test 10: Country coding 10.0 02 US 02
Test 11: Cluster code 11.0 000003 Cluster code
Test 12: Not used
Test 13: Gong test 13.0 GONG Activate gong by pressing button (gong response is delayed)
Test 14: Fault memory (not used for diagnosis)
Test 15 - 18: Not used
Test 19: Lock/unlock 19.0 L-On L-Off Lock/unlock specific test functions
Test 20: Average fuel consumption correction factor 20.0 XXX9 Press button when correct 1s position is attained
20.1 XX5X Press button when correct 10s position is attained
20.2 12XX Press button when correct 100s position is attained
Test 21: Software reset 21.0 reset Reset software

Instrument cluster, self testing

Perform the following steps to access the instrument cluster self test functions:

Remove and insert ignition key (ignition OFF)

Press and hold RIGHT cluster button. gCHECK CONTROL OKh is displayed.

Without releasing button, turn ignition switch to first dent (RADIO position). gTEST-NR. 01 is displayed.

Press LEFT cluster button for the test sub-menus.

Press RIGHT cluster button to scroll to next test.

Note:
Test 1 and 2 are always unlocked
Test 3-21 are only accessible after unlocking using TEST-NR. 19 lock/unlock function. See Instrument cluster self test, unlocking.

Instrument cluster self test, unlocking

To unlock a specific test:

Remove and insert ignition key (ignition OFF)

Press and hold RIGHT cluster button. gCHECK CONTROL OKh is displayed.

Without releasing button, turn ignition switch to first dent (RADIO position). gTEST-NR. 01 is displayed.

Use RIGHT cluster button to scroll to TEST-NR. 19 (lock/unlock)

Press LEFT cluster button once to access TEST-NR. 19 submenu. gLOCK : ONh is displayed

Use LEFT cluster button to scroll to test you wish to unlock.

Press RIGHT cluster button once to unlock desired test. Display returns to TEST-NR. 01.

Scroll to unlocked test using RIGHT cluster button.

Press LEFT cluster button to perform desired test or access that tests submenu.

Repeat unlock sequence for each test required.

Switch ignition OFF to cancel self test mode.

Note: Display shows no visual confirmation of test unlock.

Instrument cluster, software reset

To reset instrument cluster software:

Remove and insert ignition key (ignition OFF)

Press and hold RIGHT cluster button. gCHECK CONTROL OKh is displayed.

Without releasing button, turn ignition switch to first dent (RADIO position). gTEST-NR. 01 is displayed.

Use RIGHT cluster button to scroll to TEST-NR. 19 (lock/unlock)

Press LEFT cluster button once to access TEST-NR. 19 submenu. gLOCK : ONh is displayed

Use LEFT cluster button to scroll to TEST-NR. 21. gLOCK : 21 is displayed

Press Right cluster button to unlock TEST-NR. 21. Display returns to TEST-NR. 01.

Use RIGHT cluster button to scroll to TEST-NR. 21.

Use LEFT cluster button to access TEST-NT. 21 sub-menu. gREST ?h is displayed.

Press LEFT cluster button again to perform reset.

Switch ignition OFF to cancel self test mode.

Note: Display shows no visual confirmation of test unlock.

[emicen]

At a steady 80mph it should do 23-25mpg on the motorway. I managed to coax surprisingly good economy out my mate's car when using it for a few days. Given the performance that is...

[neiljohnson]

Borrowed my in laws car a few times, at 1 extreme i got 24 mpg, at the other end on a 'spirited' drive i got 7 mpg!
Overall every day driving he tends to get 18-19mpg.

[Diesel Meister]

To be fair, 18-19mpg isn't bad for a 1700kg, 400bhp car with a 4.9 litre V8.

The only thing stoping me from buying one is the cost of insuring it in central london. I do about 2-3k miles per year so fuel is the least of my concerns. Insurance and probelems ariseing from lack of use / people trying to touch park / steal it are high up the list entitled "maybe not"

[jimmycyn]

Poor MPG with an 'M' anything ?

Of course the consumption is terrible, but you have a road legal racing car, so don't moan!

MY E92 330d manual, remapped to 280BHP, will (on paper anyway) get to 60 in less than 6 seconds, and and return 35/45 MPG. I'm totally blown away with it, BUT, you 'M' guys would blow me off the road and still have time to refill before i caught up.

I'd love one but just remenber why YOU bought one in the first place

Very happy motoring

[Neil.D]

Check your thermostat - test number 7 - see if you're running cool. TStats are a common weak point. A new one will see a constant tempreture on the motorway of 78-79C.

Cooler temp will = richer running.

[jason61c]

Soovy said:

Aircon means you lost about 6mpg.

Sorry but thats utter rubbish. Aircon only uses more fuel at idle as the car ticks over a few hundred RPM higher. Maybe a total of 1.5mpg tops.