MB Fuel Consumption

Smacsor

Senior Member
Joined
Aug 26, 2012
Messages
250
Reaction score
0
Location
Bristol, UK
Your Mercedes
2013 C250 CDI AMG Sport Plus; 2011 C220 CDI Blueefficiency 125 Edition - SOLD; R230 SL500 - SOLD
Old chestnut I know but I have posted previously about MB being particularly bad regarding claimed vs actual fuel consumption compared to other marques.

Call me cynical but I wonder if the OBC figures are deliberately skewed excessively in the hope that customers will be fooled into thinking their vehicles are better than they are? The reason I say this is that my OBC has been 8.8% optimistic over the past 4000 miles.

Compare that with my VW where the OBC has UNDERestimated by 0.1% and you can see why I'm cynical.

Or is my OBC just particularly bad?

Simon
 

Argus

Senior Member
Joined
Nov 20, 2010
Messages
328
Reaction score
85
Location
Suffolk
Your Mercedes
W205 Brilliant Blue/Grey, M274
My OBC reading is about 15% out. Over 20k miles the reading is 40mpg but the actual calculated figure is 34mpg.
Quite useless really.
 

st4

Banned
Joined
Apr 6, 2008
Messages
8,624
Reaction score
2
Location
Sunny Scotland
Website
1-stephen-taylor.artistwebsites.com
Your Mercedes
Disqualified driver
Mines within 5%. So I've averaged 42.5mpg but only really 40mpg.

Goes well for a 2.1 litre. Had a brisk drive back from Kilwinning last night, and you know the sort of travel where there is brisk A road and motorway driving, the way the car can slow to take a roundabout at 30mph and be back at 70 so very quickly without really having to spank it.

That matters more than £1 per week
 

roop_the_loop

Senior Member
Joined
Mar 6, 2013
Messages
386
Reaction score
0
Your Mercedes
E220 CDI BlueEff SE, 7G auto, estate (S212), 2012
Old chestnut I know but I have posted previously about MB being particularly bad regarding claimed vs actual fuel consumption compared to other marques.

Call me cynical but I wonder if the OBC figures are deliberately skewed excessively in the hope that customers will be fooled into thinking their vehicles are better than they are? The reason I say this is that my OBC has been 8.8% optimistic over the past 4000 miles.

Compare that with my VW where the OBC has UNDERestimated by 0.1% and you can see why I'm cynical.

Or is my OBC just particularly bad?

Simon

And there I was foolishly thinking that the OBC figure is accurate, as opposed to the official gov't fairytales!

So what you're saying is that when my official figure is 53.3 (combined), and my OBC shows 42.2, what I thought was already an unacceptably large gap is actually even worse?

(Great.)

As to your point about MB being worse than others, I did see an article earlier this year saying that the gap between official and actual mpg has been growing wider in the past ten years or whatever, but if I'm not mistaken it did also say that MB was one of the biggest bull$hitters in this respect. Wish I'd saved that article, I can't remember how the different makes compared otherwise.
 
OP
Smacsor

Smacsor

Senior Member
Joined
Aug 26, 2012
Messages
250
Reaction score
0
Location
Bristol, UK
Your Mercedes
2013 C250 CDI AMG Sport Plus; 2011 C220 CDI Blueefficiency 125 Edition - SOLD; R230 SL500 - SOLD
  • Thread Starter
  • Thread starter
  • #5
Mines within 5%. So I've averaged 42.5mpg but only really 40mpg.

Goes well for a 2.1 litre. Had a brisk drive back from Kilwinning last night, and you know the sort of travel where there is brisk A road and motorway driving, the way the car can slow to take a roundabout at 30mph and be back at 70 so very quickly without really having to spank it.

That matters more than £1 per week

I agree with that Steve. Would just be nice if the OBC was reasonably accurate like a VW rather than just for entertainment value!
 

roop_the_loop

Senior Member
Joined
Mar 6, 2013
Messages
386
Reaction score
0
Your Mercedes
E220 CDI BlueEff SE, 7G auto, estate (S212), 2012
BTW, how does the OBC arrive at the mpg; where does it take the fuel consumption from? In other words, is the inaccuracy a technical problem (not being able to measure the consumption correctly - which I find hard to believe) or a 'political' one (deliberately showing the figure wrong to make it look better than it is)?
 

wemorgan

Senior Member
Joined
Apr 5, 2008
Messages
292
Reaction score
0
Your Mercedes
R172 SLK 250CDI
O
Or is my OBC just particularly bad?

Anecdotally I'm reading that the OBD on modern MB is very accurate. On my R172 it's accurate to within 1 mpg.
 

survey

Senior Member
Joined
Feb 10, 2009
Messages
768
Reaction score
22
Location
Suffolk
Your Mercedes
2012 C207 E250cdi Sport Coupe
On my 2008 C Class 220cdi Estate the brim/brim actual average mpg over 40K miles was 42.71mpg and the OBC averaged 5-6% over optimistic. On my 2012 E Class 250cdi Coupe the true average over 14K miles is 48.34mpg with the OBC is averaging 2-2.5% over optimistic. So maybe things are improving. Same style of driving.
 

MBDevotee

Senior Member
Joined
Feb 24, 2009
Messages
2,147
Reaction score
442
Location
Bristol
Your Mercedes
Dreaming of a CL55k - one day maybe....
On my ML (5.0 v8 2002) the OBC reads about 22mpg average, and i get about 18-19 in reality.

On the CLK 270CDi it reads about 49mpg but I am only getting about 39.


The OBC LIES!

I think it's because more people would be taking their cars back and whinging....

They boast about these mega economy cars, but in the real world they aren't all that good.
 

geraldrobins

Senior Member
Joined
Jan 20, 2013
Messages
835
Reaction score
61
Location
gloucester, UK
Your Mercedes
C Class/2011/200cdi
On my humble merc the obc is 4%-5% optimistic. On my previous passat the obc was 10% optimistic and about 2% optimistic on my previous bora. So I dont think mercedes are different to other manufacturers in this respect.
Regarding official figures again I think these can only be used as comparisons as everyone drives differently and does differing amount of motorway, urban and rural driving. But on the type of journey and driving style I regularly do I generally attain the official combined mpg when the ambient temperatures are over 15 deg C.
 

Devonian

Senior Member
Joined
Jan 1, 2007
Messages
413
Reaction score
3
On mySL350 over about 20 fill ups the OBC has never been more than 1 mpg out, usually only 0.5 variance
 


GAD was founded in 2009 where we developed bespoke ECU Remapping software for motorsport clients, moving forward, we have extended to road vehicles for both performance and economy,
contact GAD Tuninghttp://www.GADTuning.co.ukto discuss your requirements.
Top Bottom