[Jan van Zyl]

Hello all - does anyone know or have information how the fuel consumption figures in the advertisements/owner's manual are achieved? BMW does mention the weight of the driver and some luggage and without options - but at what speed do they travel, what ambient temperature, what height above sea level, wind-still or not, what tyre pressures, what type of tyre and/or thread remaining, what mileage of the testing vehicle and after how many tank fills. I find the figures for the 2.0 Diesel extremely optimistic - and is probably the very best that BMW achieved after all their tests - but not what the daily driver can ever hope to achieve - even if he/she drives in very moderate fashion. Thank you.

[BIMMER UK 76]

The manufacturers mpg figures must have to comply with a standard specification

2500 miles so far for my 20d and only getting 35.6mpg (slightly heavy right foot, 18" rims with auto transmission and only a little air con useage)

[sfax]

My average is about 35mpg after 4000 miles or so. I can get about 40-43 on a motorway run if I keep to about 70 and there aren't many hills. I notice that ascents have a bigger impact than they did with my last car, presumably because of the weight.

The official figures are only good for comparison with other cars IMO. They are recorded on a rolling road with no wind resistance. Even taking that into account, I think the figures are very optimistic for the 20d.

Some people have got 42 average. The 17" non-run flat tyres will help in that respect but I could never average out that high unless I drove it super slowly

[Bimar]

Originally Posted by Jan van Zyl

Hello all - does anyone know or have information how the fuel consumption figures in the advertisements/owner's manual are achieved? BMW does mention the weight of the driver and some luggage and without options - but at what speed do they travel, what ambient temperature, what height above sea level, wind-still or not, what tyre pressures, what type of tyre and/or thread remaining, what mileage of the testing vehicle and after how many tank fills. I find the figures for the 2.0 Diesel extremely optimistic - and is probably the very best that BMW achieved after all their tests - but not what the daily driver can ever hope to achieve - even if he/she drives in very moderate fashion. Thank you.

What are you currently getting city and highway driving?

[robwoods]

I have the 20d, only done about 800 miles so far.

I get about 33mpg on the 4-5 miles commute to work on urban local roads

I did the 140 miles drive from Nottingham to London last Wednesday and got 47mpg one way and 46mpg the other way. That was with cruise set to 75mph on the motorway and just keeping up with traffic in the masses of roadworks. Included 15 miles of crawling traffic on M25.

You have to drive like Miss Daisy's elderly relative to get those figures, but the 20d with auto gearbox that I have doesn't really encourage 'sporty' driving. It's not very quick. I wasn't accelerating hard ever, just building up speed in a normal way.

I have the 17" non-runflats, auto, 20d.

[ninoo]

1500 mls up on 2.0d auto ,mixed driving conditions ,no agressive driving' ave 40.7 mpg since new ,reasonably happy with this figure. 17" non runflats.

[robwoods]

I wonder how the fuel consumption improves as the engine gets run in a 4 cylinder diesel. At what point would it be likely to be run-in enough such that the fuel consumption would be unlikely to improve any further?

[Lotus7]

Originally Posted by Jan van Zyl

Hello all - does anyone know or have information how the fuel consumption figures in the advertisements/owner's manual are achieved? BMW does mention the weight of the driver and some luggage and without options - but at what speed do they travel, what ambient temperature, what height above sea level, wind-still or not, what tyre pressures, what type of tyre and/or thread remaining, what mileage of the testing vehicle and after how many tank fills. I find the figures for the 2.0 Diesel extremely optimistic - and is probably the very best that BMW achieved after all their tests - but not what the daily driver can ever hope to achieve - even if he/she drives in very moderate fashion. Thank you.

BMW generally uses figures achieved by running the vehicle through the NEDC (New European Driving Cycle). This is a fixed program of acceleration, cruising and braking on a chassis dynamometer that is supposed to simulate typical urban driving in Europe. It has been criticized because the acceleration cycles and maximum speeds are less than what normal traffic often requires. During the cycle, fuel consumption and emissions are carefully measured under laboratory conditions.

Some parameters for the NEDC are:

Temperature: Car is held at 20 to 30 deg. C. for at least 6 hours before test.
Car is "driven" immediately after start-up. No warm up idle is allowed.
Total Distance Traveled: 11.007 km
Duration: 19.66 minutes
Mean speed: 33.6 km/hr.
Max speed: 120km/hr.
Max. Acceleration Rate achieved: 0-100km/hr in 10.0 seconds
(0-90km/hr used for certain “low-power” vehicles)

Logged measurements must include:
Fuel consumption as L/100km
Pollutant Emissions (HC, CO, NOx, CO2)

The ratings achieved are generally better than most drivers get in "real world" conditions, but are useful as a relative comparison of different vehicles with each other.

[Vintage]

Originally Posted by BIMMER UK 76

The manufacturers mpg figures must have to comply with a standard specification

2500 miles so far for my 20d and only getting 35.6mpg (slightly heavy right foot, 18" rims with auto transmission and only a little air con useage)

It makes me so mad we can't buy the 20d in the US - I would kill for it.

[Redbhuna]

Done 1100 miles in my Auto 20D with 17"'s. Computer says 45.1mpg. I do a 30-35 minute commute up and down the M1 mainly and love to sit back and let the cruise control take the strain at 60-65mph , rarely go above 70 because there's no need. Last full tank gave me 630 miles with about 40 left at fill up.

[sfax]

Originally Posted by Redbhuna

Done 1100 miles in my Auto 20D with 17"'s. Computer says 45.1mpg. I do a 30-35 minute commute up and down the M1 mainly and love to sit back and let the cruise control take the strain at 60-65mph , rarely go above 70 because there's no need. Last full tank gave me 630 miles with about 40 left at fill up.

That is very impressive but makes sense based on the average speed. I find hills make a much bigger difference than they did in my last car, presumably because of the extra weight.

[Redbhuna]

Yeah, Urban mileage is a lot lower in this than my previous 120D. I don't care though!

[clivem2]

Originally Posted by Redbhuna

Yeah, Urban mileage is a lot lower in this than my previous 120D. I don't care though!

I'm hoping my 3.0D will significantly improve on the 19 mpg I get around town in my 335i!

[Jan van Zyl]

Thank you for all the input - these answers do clear up a lot of things for me. Official BMW figures are: Urban - 6.1/100km equals 38.81 US mpg equals 46.78 UK mpg; extra-urban - 5.3l/100km or 44.67 US mpg or 53.85 UK mpg; combined - 5.6l/100km or 42.28 US mpg or 50.96 UK mpg. Mine currently - 7.56l/100km or 31.31 US mpg or 37.74 UK mpg (mostly town driving). I'm glad to see especially UK figures coming close to the official BMW claims - and will now try a bit harder to improve my figures.

[tank531]

reference to Lotus piece on the EU std fuel consumption test - I read a UK car publication last month (can't recall the title) and it tested in real life and in the lab a hybrid something, a RR Sport and a BMW 1xx. The RR Sport acutal bettered the official EU manufacturers fuel figures and the other 2 were about 88% in a combined cycle, real world driving test. Apparently the larger vehicle producers have no incentive to get the figures down by using such tricks as small wheels/tyres, detuned CO2 engine or other 'allowable' fudge of the figures. They are not selling large cars on fuel efficiency in the way you might buy a small car.

The only way to get your fuel consumption down is slow down - a personal choice.

[clarence]

Originally Posted by tank531

I read a UK car publication last month (can't recall the title) and it tested in real life and in the lab a hybrid something, a RR Sport and a BMW 1xx.

It's an article from Autocar. They tested 4 cars using the same route at the same time of the day. The Range Rover & Skyline GT-R managed to beat official claims whereas the Honda CR-Z & BMW 320d ED (the special 320d) did not.

[sfax]

Originally Posted by tank531

reference to Lotus piece on the EU std fuel consumption test - I read a UK car publication last month (can't recall the title) and it tested in real life and in the lab a hybrid something, a RR Sport and a BMW 1xx. The RR Sport acutal bettered the official EU manufacturers fuel figures and the other 2 were about 88% in a combined cycle, real world driving test. Apparently the larger vehicle producers have no incentive to get the figures down by using such tricks as small wheels/tyres, detuned CO2 engine or other 'allowable' fudge of the figures. They are not selling large cars on fuel efficiency in the way you might buy a small car.

The only way to get your fuel consumption down is slow down - a personal choice.

Interesting. I'm amazed any of the models beat the official consumption figures. 88% sounds more like it. All depends on the technicalities of the testing though really. The official mpg remains a good way to compare one model to another. Being able to match or better it depends on how you drive, where you drive, what you drive on, how much weight in the car, what the temperature is, etc etc

[Bimar]

Originally Posted by clarence

The Range Rover & Skyline GT-R managed to beat official claims

What a bonus for these gas guzzlers...like it will make much difference $$$$ wise at the pump.

[clarence]

Originally Posted by inamik75

What a bonus for these gas guzzlers...like it will make much difference $$$$ wise at the pump.

The RR is a diesel, so not as a gas guzzler as the 5.0 V8 version. The point is, small engined versions may not be the most economical in the real world as u'll need to push hard to keep up in real world traffic situations. Also the NEDC Urban figure for X3 35i beats the X3 28i by quite a margin, I guess this will also be the case in the real world.

[Lotus7]

For anyone interested, here's a speed vs. time graph of the full NEDC cycle used to measure fuel consumption. It's a pretty slow drive with a fair amount of time spent stopped. Acceleration is also pretty slow and the average speed is a paltry 33.6 kph (21 mph) The graph is from a paper by E. Tzirakis. Sorry for the poor quality reproduction, but it is readable.

[Bill S]

Only done 700ml so far, engine now starting to rev more freely but I'm still keeping revs below 2000 except for very brief extensions.
That gives almost 90 in the 3.0 so no current wish to go much faster

I'm quite surprised that 2000rpm max. is not such a bind - no problem overtaking with plenty of go.

Most of my driving has been country roads around Northumberland - only one 100ml trip on motorway. I did not feel speed restricted at all

So having given the perspective - the fuel consumption - total so far from new 36.7mpg

On motorway (M6 Penrith & over Shap) the mpg was up to 43 overall - much lower up the hills but recovered very nicely coming down!
It is also noticeable that consumption is heavier for the first few miles after startup so long trips will give better mpg - I've only done 1 trip over 30miles so far.

I have to say I'm well pleased with the consumption for a 3 litre engine!