Mpg

[baxlin]

Filled up my W204 C220 yesterday, the 'from reset' figures were 400+ miles, and 53.3mpg. As a lot of the driving was short runs to and from work, I was happy with this. (the car's done less than 5000 miles)

But doing the brim to brim, first time I've done it on this car, and using 1ltr = 0.22 gallons, it came out at 49.9mpg. I suppose less than 10% error isn't too bad, but with all the latest electronics etc, I was hoping the readout would be close to correct.


Am I asking too much?

Malcolm

 

[Troon]

You need to average over a few tanks to get a properly accurate real figure. Here are my results, which show only slightly better accuracy than yours.

http://www.mbclub.co.uk/forums/electronics/129722-trip-computer-mpg-accuracy.html

 

[V12]

At least you know and accept it's not accurate. ..unlike half of the rest of the forum! ;-)

It can be corrected on a star machine with developer mode.

 

[Dieselman]

I wouldn't be unhappy with 50mpg, but Troon's figure of 38-40mpg is only a bit better than my old 6 cylinder clunker.

 

[Troon]

I wouldn't be unhappy with 50mpg, but Troon's figure of 38-40mpg is only a bit better than my old 6 cylinder clunker.

Mine's an S211: the estate bodystyle makes quite a detrimental difference, and I sometimes have bikes on the roof or towbar. I typically get mid-40s on a run where I'm not caring about FE, and can see well over 50 on the OBC on gentle runs if I'm careful.

Your point is valid though — engine displacement and fuel consumption are not proportionally-related.

 

[cinek]

My 220 returned 47.1 over 10000 miles.

If I am on empty motorway, stick the cruise on and puddle along at around 60mph, the economy goes up to around 60 miles/gallon.
Each time I get stuck in traffic, accelerate, slow down, accelerate, and so on, it goes straight back to 50 miles a gallon.

Although I spend a lot of time on the motorways (mostly M25), I equally spend a lot of time in London, so I cant imagine these figures get any better.

 

[Deleted member 37751]

Your point is valid though — engine displacement and fuel consumption are not proportionally-related.

Mercedes have a history of making engines of differing sizes doing roughly the same mpg.

 

[Troon]

Mercedes have a history of making engines of differing sizes doing roughly the same mpg.

Not just MB, either. The 6-pot diesel XF is very close to the 4-pot in real world. Once the WLTP comes into force, the published numbers will demonstrate this far better than the NEDC.

 

[Dieselman]

For any given body there is a set amount of power required to drive it along. If the diesel engine is modular, the only real difference is friction due to more cylinders, hence fuel economy should be broadly similar when driving, but not when idling or under low load.

 

[grahamcarvlin]

Hi,

I do a 28 mile run to work each day, and 28 mile back obviously. The majority of this on cruise at 63 mph on dual carraigeway. Just had the car two weeks, its an ex demonstrator with 7000 mile on it. The average is 49.6 mpg according to the trip computer. This with a max so far of 55.4 mpg on the best trip. To be honest I am disappointed as for the last 5 or 6 cars I have had I have always averaged better than the quoted combined figure. For this 220 coupe that is 53.3 mpg. I was hoping for better but it seems to be worse than some of your figures. I intend to see how it develops over the next few tank fulls and hope it improves.

 

[Frugal]

I foumd that my c250cdi's mpg has improved steadily with time (33k miles now from new), allowing for seasonal adjustment. Trip computer is around 7% optimistic which pretty poor but it's consistant so I'm not too bothered.

 

[V12]

Mercedes have a history of making engines of differing sizes doing roughly the same mpg.

The best example was the W140. The real world difference in consumption between a 6.0 V12 and a 2.8 I6 was minimal.

The real world servicing costs on the other hand...

 

[grahamcarvlin]

Quick update. Filled the car up at the weekend and the trip computer showed 47.9mpg over 1500 miles. Calculated on the last tank was 45mpg. I drive this car the same as my last few main cars (like an old man I am told !!) and am well dissappointed with this. Its around 8 mpg less than I realistically expected based on 20 years of similar driving over quite a number of cars. I hope it improves cause its adding to my fuel bill by a fair amount unexpectedly and niggling me a bit too much.

 

[wemorgan]

Hi,

I do a 28 mile run to work each day, and 28 mile back obviously. The majority of this on cruise at 63 mph on dual carraigeway. Just had the car two weeks, its an ex demonstrator with 7000 mile on it. The average is 49.6 mpg according to the trip computer. This with a max so far of 55.4 mpg on the best trip. To be honest I am disappointed as for the last 5 or 6 cars I have had I have always averaged better than the quoted combined figure. For this 220 coupe that is 53.3 mpg. I was hoping for better but it seems to be worse than some of your figures. I intend to see how it develops over the next few tank fulls and hope it improves.

That's a similar journey to myself. I've the 250 engine in a SLK and average 50mpg brim to brim and on the OBD. It would be 2-3mpg more if it wasn't for a steep hill I climb each day. The engine does seem very sensitive to load and the mpg quickly drops away with urban driving or inclines.

 

[V12]

Quick update. Filled the car up at the weekend and the trip computer showed 47.9mpg over 1500 miles. Calculated on the last tank was 45mpg. I drive this car the same as my last few main cars (like an old man I am told !!) and am well dissappointed with this. Its around 8 mpg less than I realistically expected based on 20 years of similar driving over quite a number of cars. I hope it improves cause its adding to my fuel bill by a fair amount unexpectedly and niggling me a bit too much.

I think you're doing well to get 45mpg over short journeys.

What were you expecting?

 

[wemorgan]

Is 28 miles so short? I'd imagine 28 miles on mostly dual carriage ways to give near optimal performance.

 

[DITTRICH]

There are so many variables, even with the brim to brim method, that anything within 10% of the on board computer is probably fine IMHO. No-one should expect the test figures to be replicated in the real world. Many years ago MB used to quote fuel consumption at a steady 90km/h and 120km/h as well as the test figures. As a result, I look towards the steady state figures when trying to work out whether my car is okay or not. My 3 litre diesel s124 is capable of 40-45mpg at a steady 50mph which for a 20 year old barge isn't bad.

 

[V12]

Is 28 miles so short? I'd imagine 28 miles on mostly dual carriage ways to give near optimal performance.

Sorry, getting the OP and grahamcarvlin mixed up!

28 miles is a good trip and should be able to get near maximum depending on the road conditions.

 

[Billigmeister]

Quick update. Filled the car up at the weekend and the trip computer showed 47.9mpg over 1500 miles. Calculated on the last tank was 45mpg. I drive this car the same as my last few main cars (like an old man I am told !!) and am well dissappointed with this. Its around 8 mpg less than I realistically expected based on 20 years of similar driving over quite a number of cars. I hope it improves cause its adding to my fuel bill by a fair amount unexpectedly and niggling me a bit too much.

i have a feeling you are going to have to get used to those sorts of figures.

lots of people talk here about mpg and you will see most do not get anywhere near the official figures. some do but a lot don't.

 

[yezz]

I am averaging 4.7l/100 km / 60 mpg (UK) / 50 mpg (US) on long journeys with my old W203 C200. The above 45+ is still okey I think. If I wanted less I would be driving some VW lupo or G-wiz which is never going to happen