C250 CDi Blue Efficiency - MPG?

[mon2s]

Hi all, I've been running a C250 CDi (auto) for a couple of weeks now. Bought it as an ex MB management car with 3k on the clock.

When I picked it up I noted the trip computer showed fuel consumption of 29.1mpg for the 3000 miles on the clock. I was worried that the previous driver had thrashed my new motor.

However having now driven it myself (gently) for around 600 miles, the best I've managed is 34mpg with an average of 31mpg. No rush hour traffic or major jams, just gentle average speeds some A road and motorway and some urban. As the Blue Efficiency blurb gives mpg figs for the auto at 35 urban, 55 extra urban and 47 combined I'm thinking there is either something wrong with my car or the promotional material is wildly exaggerated. I figure if I drove the car hard or was in lots of traffic, I'd be looking at 25mpg at best!! Anyone else got any 'real life' MPG figures for the diesel 250?

Love the car but horrified at the current MPG figures. Could this be to do with the injectors I've just read so much about? Aaargh !

 

[johny5_uk]

It will because of the cold weather and mainly because its new.
I am in the same boat with my E350, the mpg is way below the stock reports but it will get better in time.

Welcome to the forum btw and I hope your car lasts the dreaded injector bug!

 

[st4]

Be thankful the car is moving and not broken down....

A new diesel takes time to "bed in" its MPG will improve in time. Its also winter time, so MPG does drop due to the additional anti wax agent in diesel, greater heatloss (and therefore energy which comes from the fuel). It will get better.

Some tips to bear in mind.

Avoid harsh acceleration
use the manual overide to ensure it changes gear no higher than 2k rpm (any higher is just wasteful)
check tyres etc are correctly inflated
use decent i.e. non supermarket fuel
drive smoothly (harsh braking and acceleration no good)

 

[mon2s]

Thanks for the replies folks. I look forward to warmer weather and a nicely loosened engine but even then I can't see how the MPG can improve by 15MPG from my current consumption to the combined 47MPG that sold the car to me.

I'm pretty certain my driving could not be much more economical - I've matched the manufacturer MPG figures on my last two diesels (when I've tried to - I'm not a saint all of the time!!)

 

[Colin_b]

That only 10% better than my SLK 350!

 

[trapperjohn]

*** also not a saint. But he does get good MPG from his car - if he wants too.

 

[wemorgan]

Your journeys look like a typical mixed cycle to me, but how long are your journeys?

Nearly all of mine are 2-3hrs long, so the engine fully warms up and I see little or no drop if efficiency. In fact when there was snow on the road, I slowed down and saw an increase in efficiency.

As Steve said, smooth driving, correct tyre pressures go a long way to improve matters. Climate control on my car also reduces efficiency by ~5%

BTW: last week I tried double hard and achieved 70.6mpg over 300 miles. Chuffed Want to swap cars?

 

[KNU7S]

My wife used the C220 Cdi for the school run (2 mile round trip) and the tesco run and always is 30mpg+

 

[st4]

*** also not a saint. But he does get good MPG from his car - if he wants too.

http://www.MBClub.co.uk/forums/members/***-albums-my-e-class-picture885-how-beat-combined-cycle.jpg

Very good MPG-this was in summer, a similar driving style and I struggle for 40mpg now because of the cold. Normally I push a bit faster though

When that pic was taken, no a/c, window down. Now using heating + ac (stops misting) so much more drain on the car

 

[whitenemesis]

Your journeys look like a typical mixed cycle to me, but how long are your journeys?

Nearly all of mine are 2-3hrs long, so the engine fully warms up and I see little or no drop if efficiency. In fact when there was snow on the road, I slowed down and saw an increase in efficiency.

As Steve said, smooth driving, correct tyre pressures go a long way to improve matters. Climate control on my car also reduces efficiency by ~5%

BTW: last week I tried double hard and achieved 70.6mpg over 300 miles. Chuffed Want to swap cars?

Ditto Mine went up to 54mpg

 

[Rory]

Thanks for the replies folks. I look forward to warmer weather and a nicely loosened engine but even then I can't see how the MPG can improve by 15MPG from my current consumption to the combined 47MPG that sold the car to me.

I'm pretty certain my driving could not be much more economical - I've matched the manufacturer MPG figures on my last two diesels (when I've tried to - I'm not a saint all of the time!!)

We get these threads often and people talk about tyre pressures, not using climate, engine loosening up etc etc but I agree with you - unless you're doing lots of really short journeys, which seems unlikely if you've done 600 miles in a couple of weeks, then the difference is too great.

I've always had good MPG off the bat with my cars.

Bear in mind the figures aren't MB's - they come from an EU test. Having said that, an owner in Germany sued and won damages against MB and his fuel consumption on an S Class was only 9% out.

 

[timskemp]

Tyre pressures are an important one. Also in winter the management system has ways of increasing warm up speed (aux heaters, higher idle, higher change points) and running things like heated screens, plus the lower speeds and more stop-start nature of winter driving, all conspire to a much worse figure in winter to summer.

Any idling before the engine is to working temp will be horrific to your averages.

 

[biggusmickus]

I drive a manual E250cdi and am getting 40-44mpg on a long commute with a bit of local roads messing about at either end. I do drive it like I've stolen it so with a bit more decorum I guess that it could be more like high 40s maybe 50. I might leave home earlier one day and try it. IIRC it's just shy of 13,000 miles so it should be starting to loosen up.

 

[mon2s]

I'll remain patient for a few more weeks before approaching MB if things aren't improving (significantly!).

Just to confim that the A/C is off, the box is in Comfort mode and most of my journeys are a minimum of 10 miles.

As I've said previously, I've run various diesels over recent years including a V6 3.0 and none of them were any where near as poor on economy as this one regardless of how new they were or how cold it was. Considering technology has moved on, I would be expecting to at least match my previous motors mpg.

I think the problem must be with my car because I would think there would be quite a few owners of 250's complaining if the consumption was so far off the advertised figures. So far I haven't come across any.

 

[Branko]

Same engine but in an E class. Have driven 2,800 miles since picking it up in October 09 and over this period the average according to the car is 32.6. I do lots of short journeys though. On a drive I got it to 41mpg. Hope it improves but am also hoping the injectors don't fail !!

 

[Rory]

Tyre pressures are an important one.

Nope - they make hardly any difference. Many articles say it makes a big difference but read actual test results and it's surprisingly marginal.

As you noted, there are all sorts of little effects; another one is that winter diesel (mid Sept to Mid March) knocks 2-3MPG off. The main variable effect that we don't know anything about the kind of journey's and the type of driver the OP is.

However, given reasonable length (12 miles+) journeys in not too busy traffic and not aggressively driven, then I'd be most dismayed if the car wasn't easily doing 40MPG+.

 

[wemorgan]

I think the problem must be with my car

I think you could well be right. On other forums & OEMs I've read similar things. 9/10 the customer is told to wait for the engine to bed-in or it’s to do with their driving style.

But like you across a wide range of cars, new and old, I can normally get close enough to the stated MPG figures.

I think you will have to be strong willed and persevere if you want a satisfactory conclusion.

 

[mobiledreams12]

Easily get 48mpg tootling up and down the M1. 100 miles each way.

 

[mon2s]

Easily get 48mpg tootling up and down the M1. 100 miles each way.

Well that's what I would expect to easily be achieving in my guzzler considering it is the quoted MPG figure on the combined cycle. God knows how they came up with the quoted 64.2mpg for the extra urban figures.

I've just returned from a nice smooth 30 mile A road and motorway run. No traffic hold ups, didn't go above 70 on the motorway and a steady 50 on the A roads - My best MPG yet - 37 showing on the trip! In my previous car (Golf GT 170PS) It would be close to 55mpg on that journey and I would have been going faster too!!

 

[wemorgan]

Just a thought, though most unlikely: Is the trip metre reading US gallons I wonder?
37mpg (US) = 44 mpg (UK)

Or are you working out the mpg by filled tank to filled tank?