C250 TD - poor mpg

paulfoel

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Hi,

I've had a '99 C250TD for about a week now and have just filled up the car with Diesel (it was full when I picked it up).

By my calculations, I've only got about 29 mpg which is a little disappointing. I know its a big car and it is 2.5 but this still seems a little low.

Its been mostly urban driving but some motorway, and, of course, the a/c has been going full tilt recently.

The only other thing I can think of is me getting used to the style of driving a diesel auto. I've had a diesel before (audi a4 manual - 50mpg!) and know that accelarating is more of a constant press down on the accel. pedal...

However, my last car was a 2.0 petrol Hyundai Coupe SE. Instant throttle response etc...

Whats everyone else get or expect ? (BTW. Anybody know where I can get official mpg figures?)
 

Steve_Perry

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For official figures you could try Parkers Guide

*EDIT* Just looking at this page quotes figures for your car as:
Mercedes C250 TD - 38.1mpg

Your other good bet is to compare notes with Jimmy as he also drives a C250TD. As for me it depends on whether I am motorway cruising, approx 34mpg or driving like a tw@t around town where it can drop as low as 20mpg. Most of my driving is the latter :p ;) which reminds me... I need to fill up at lunch-time.

S.
 
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RichardM

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That doesn't sound very good Paul. Over the last 500 miles with the air con all the time I've averaged just over 39mpg. Thats not driving it slowly either. Even around town and driving hard on country roads the average never goes below 33.
 

jimmy

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I get about the same for lacal driving, I was down to 24mpg at one time when I first got the car. The best I have achieved is 36mpg whilst on holiday doing long motorway trips keeping to below 80.

I too was a bit dissapointed as MB claim 42mpg, but like you say it is a biggish car and performs well.

By the way I have just chipped mine myself about half an hour ago..............wow.:bannana: :bannana:
 

fuzzer

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Remember that the 250 TD engine isnt CDI. Its the CDI that makes the diference on the MPG.

Our E220 CDI does 46mpg .
 

jaymanek

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Also, when you picked it up, it may not have been full FULL if you know what i mean.

When i return hire vans, i only fill them up so that the guage reads full, but theres usually still room for at least another fiver...

Best to recalculate next time you fill...
 

Fudger

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Paul, I had a C250TD sport for 60k miles and averaged 35mpg with mixed driving.

IT WAS A VERY GOOD CAR FOR ME...one of the best I have had.

J.
 
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paulfoel

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Originally posted by RichardM
That doesn't sound very good Paul. Over the last 500 miles with the air con all the time I've averaged just over 39mpg. Thats not driving it slowly either. Even around town and driving hard on country roads the average never goes below 33.

Richard. Thats much better than mine !
 
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paulfoel

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Originally posted by fuzzer
Remember that the 250 TD engine isnt CDI. Its the CDI that makes the diference on the MPG.

Our E220 CDI does 46mpg .

So what exactly is the difference between a normal TD and a CDI?

Is it just performance? (i.e. 250TD is turbocharged and CDI is'nt?)

Hmm. Used to have an Audi A4 TDI and that managed 50mpg. Admitedly, although still Turbo it was 90bhp bot that 150 bhp of the C250TD...
 
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paulfoel

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Originally posted by jaymanek
Also, when you picked it up, it may not have been full FULL if you know what i mean.

When i return hire vans, i only fill them up so that the guage reads full, but theres usually still room for at least another fiver...

Best to recalculate next time you fill...

Yeh. I did think that to be honest....

However, gauge did seem to stay above full for a good 80-90 miles.... (Done about 40 on this tank so far and it still has'nt moved!)
 

Steve_Perry

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Originally posted by paulfoel
So what exactly is the difference between a normal TD and a CDI?

I believe CDI is Mercedes' term for their common rail diesel injection technology that gives benefits of increased economy and engine refinement/smoothness. *EDIT* I think CDI allows the ECU (engine's management computer) greater accuracy and finer control over the volume of fuel injected into each cylinder when compared to the older fuel injection systems.

Although your C250TD has a turbo, the engine uses the older form of fuel injection.

I guess it's analogous to the change years ago where car manufacturers changed from carburettor technology over to fuel injection systems. I think all MB's (if not most manufacturers) now only use common rail fuel injection for their diesel engines.

I'm sure some of the other guys here could elaborate in further detail or put me straight if I've got something wrong ;)

S.
 
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jimmy

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Originally posted by paulfoel
So what exactly is the difference between a normal TD and a CDI?

Is it just performance? (i.e. 250TD is turbocharged and CDI is'nt?)

Hmm. Used to have an Audi A4 TDI and that managed 50mpg. Admitedly, although still Turbo it was 90bhp bot that 150 bhp of the C250TD...

CDi is the newer common rail technology, the fuel is pressurised to a much high pressure when being injected into the cylinders. This creates a finer mist and so you get a cleaner more efficient burn.

Both CDi and TDi engines have a turbo and intercooler, the 220CDi is less horsepower bu develops more torque or turning effort which is more important than horsepower.

The A4 TDi is only a 1.9litre and only develops 90bhp although there are 110 and 130 and even 150bhp versions of the same engine. Also, automatics use slightly more fuel.

As I have said, I get about 28-30mpg for every day driving, a bit more on longer trips. All TD engines seem to have a good thirst when driven over 79.9mph in my experience. As soon as you go over 80mph you can see the fuel level drop.:D

I reckon if I drive mine sensibly now it has been chipped I should get more MPG as you don't have to press the pedal so hard/far to get the same results.
 

RichardM

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Originally posted by jimmy
All TD engines seem to have a good thirst when driven over 79.9mph in my experience. As soon as you go over 80mph you can see the fuel level drop.:D

Thats interesting, I drove all the way to Birmingham last sunday morning, about 125 miles with the cruise control set to 90 all the way there (no traffic at that time on a sunday morning) and it did 44mpg average for the journey. I haven't noticed a difference driving under 80mph but then its not something I do very often!
 

jimmy

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Originally posted by RichardM
Thats interesting, I drove all the way to Birmingham last sunday morning, about 125 miles with the cruise control set to 90 all the way there (no traffic at that time on a sunday morning) and it did 44mpg average for the journey. I haven't noticed a difference driving under 80mph but then its not something I do very often!

Thats why I said TD engines not CDi. My Vito 112CDi would do 35mpg all the time.:D
 

RichardM

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Sorry, mine is still a turbo diesel so I thought you were referring to all turbo diesels.
 
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paulfoel

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Originally posted by jimmy

As I have said, I get about 28-30mpg for every day driving, a bit more on longer trips. All TD engines seem to have a good thirst when driven over 79.9mph in my experience. As soon as you go over 80mph you can see the fuel level drop.:D

Hmmm. OK. Maybe I've been spolit with owning smaller engined Diesels in the past...

Still a bit disappointing when the official figures are around 38mpg.
 

fuzzer

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Originally posted by jimmy
As soon as you go over 80mph you can see the fuel level drop.:D

I was getting 40.1 sitting at 80 in my C180k which is superb.

at 80 our E220 CDI does about 43-46 mpg.

Considering that the diesel costs a few thousand more.. is it really worth the extra. ??
 

RichardM

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I think its worth it for the power. I test drove the E240 and found it much more sluggish and I'm sure that wouldn't be that economical. I can't see the E200 being too quick either even if it offers more mpg than the 240.

I read an article that said the second hand value of diesels is likely to drop because there are so many being registered and traditionally second hand buyers preferred petrol cars, so a petrol passat is likely to fetch more than a diesel one because there will be fewer around.
 
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