Low Poor MPG C220 CDi W203

[naim22]

Hello there!

I have a problem with my new car and was hoping for some help here. I am new to these forums but this is my second mercedes (out of 4 cars total, used to have a 190D)

I have recently bought a 2006 C220 CDi Auto, and its returning some ghastly mpg (had a passat tdi before this so expected a hit but not to this extent). The car averages 28mpg town and city driving which I actually thought was acceptable. I know automatic is quite a drain on fuel so was not surprised. However I just took the car on a 70 mile run on the M1 maintaining 60-70 mph as much as possible and got some real disappointing figures compared to other 200/220 cdi's I have seen for myself.

This car has lived in London before me, however I have given it some pretty decent runs to regenerate the DPF (hopefully). There are no lights on etc. It has had its turbo replaced about 1 year ago aswell and does not struggle for power at any point so I think the MAF is ok. I wondered if some sort of reset may cure it as it is used to London city driving? or maybe I need to give it some more Italian tune-ups

I took a photo of my cluster at the end of the journey, I heard low coolant temp can cause poor mpg, however my car does not really drop below 80 degrees and the heater appears to operate fine

I would like to get it on STAR if possible should noone be able to tell on here. Is there anyone in the Warwick/Leamington Spa area who does this?

 

[DSM10000]

The water temperature may be a little low, I would have thought that 88-92 degrees C would have been more normal a range.

 

[joecash]

The water temperature may be a little low, I would have thought that 88-92 degrees C would have been more normal a range.

doesn't it look around that - mind you I haven't been to spec savers lately

how about servicing record - binding brakes - tracking etc etc

 

[naim22]

It has been well serviced with Mercedes FSH up till about 70k, thereafter has been serviced regularly with Genuine Mercedes parts by a local mechanic

I dont know but when I let off the accelerator it does sometimes feel like there is something 'tugging back' on it for a fraction of a second. I put this down to it being an auto though my 190D never did this?

Tracking has been recently done as far as I am aware, Tyre pressures were checked yesterday. I dont believe any brakes are binding as the car does not pull in any direction whilst braking. I shall double check though.

Thanks

 

[joecash]

only other thing I would suggest is to check the air filter - after that you are looking at the expense of checking out mechanical and electrical issues of which I know so little that I would be considered dangerous!! I therefore defer to those with engineering expertise to offer you words of wisdom

 

[naim22]

Ok, thanks I will take a look at the air filter although I think it was changed upon last service around 8000 miles ago.

Does anyone know if my car has a DPF or not? I am reading conflicting opinions on whether it has one, if so it may be that it could be at fault. At the moment I am convinced it has no DPF so cannot think why it would be overfuelling

I could of course be wrong and may just need to accept that these cars arent great on MPG, I still enjoy driving it though loads I would have probably gone all out for a C350 V6 if I knew the fuel economy was this bad!

 

[joecash]

Believe it or not my son's w211 e320 cdi Inline 6 without DPF will return around 42mpg on a 32 mile each way daily work run with 20 miles motorway e/w.

 

[grumpyoldgit]

I'm not convinced these read outs are very accurate. I've just been out to check my C270 CDI as a comparison, it's been parked up for about an hour before I took the snap, so has cooled down a bit, but the temperature normally sits about the same place as yours, just above the 80º mark.

I always use S setting for the gearbox. Noticed yours is in C.
Might also be worthwhile giving it a dose of injector cleaner / fuel additive to see if that helps.

Anyway here's my reading for today, driving on local A & B roads and also country lanes, no m'ways and no dual carriage ways.....
I think the only way to get an accurate reading is to calculate it yourself.

Edit: P.S. Forgot to say, if you post up your VIN number someone will be able to check the data card regarding it having a DPF.

 

[flango]

If we are saying 28 mpg around town and 44 mpg on a run that's perfectly normal from my experience of them. It will never be in the VW league and my Volvo V70 at 70 mph does about 63 mpg and has a long term average over 40,000 miles of over 57 mpg. If a diesel doesn't do over 50 mpg then theres no point having one and you might has well get a petrol and lose all the tractor clatter.

 

[naim22]

Thanks, my VIN number is WDC2030082R249473, if anyone can give me the datacard for this car that would be great.

So you think my figures are normal? to get 44 I had to be mega careful and stick to 60mph bar the odd caravan overtake, no cruise, no A/C etc. on a normal 80mph run I would get about 39. It's odd because my neighbour owns a C200 CDi auto, same year as mine and his mpg figures blow mine out the water. we are talking no lower than 36 for him really. he drives mostly round town too.

grumpyoldgit those are fantastic figures for a C270, surely it should be more thirsty? I guess my car has to 'work harder' but it's not exactly short on go and there is always power whenever I need it. plus being only 20 means insurance is still a bit steep! I also notice that your avg speed is much lower than mine, so those really are great figures. I've never seen my car get to 47 ever.

Yes I knew when I gave up the VW I would never see that good mpg again. That car gave me 58mpg average on a 50 mile run at 60mph once. However it does lack the 3 pointed star/auto box that puts a smile on my face, (if I stare at the badge long enough the mpg display soon disappears!). I even made one out of coathanger for my VW but it just wasnt the same

thanks for all the help

 

[vealige]

MPG problems are a strange one and can be down to many things. If you were experiencing bad MPG on your Passat for example I would say it was the temp sensor which costs £8 to replace and is a common problem. To be honest lots of variables can have an effect on your MPG from type of tyres, pressures, how well serviced the car is so are all the oils news such as gearbox, engine, diff, power steering etc... its worth changing things like the temp sensor on a car as it is surprising what difference it can make.

On my bora I changed the gearbox oil for a non VW oil and it lowered the mpg by 3-4 mpg on a long run as vw gearbox oil is really thin for example.

So really start off with the cheap things first of all make sure everything is as it should be such as no leaks from intercooler pipework, brakes not binding and so on before spending money on diags which may tell you very little.

 

[Tinkerer]

1) don't trust the figures from the trip computer, I have not yet had one of these that is accurate when compared to tank to tank mileage.
2) Average mpg on my 2001 w210 was 44 on reasonable, 30 mile runs not in town, and if I took it steady the best I could get was 50mpg, 45 with good squirt and speed on the motorway. Temperature should be 90C and as far as I was aware is not controlled by the gauge as you can check the opening temp off the car in a saucepan.

 

[grumpyoldgit]

Data Card Details from the Russian site, the only one I have access to and to the best of my knowledge the code for DPF is 474, which your car doesn't have.
Perhaps someone with access to the UK MB site can confirm these details.....
Or you could ring your local MB Dealer and ask them, just give them your VIN number.

 

[Rory]

I'm not convinced these read outs are very accurate. I've just been out to check my C270 CDI as a comparison, it's been parked up for about an hour before I took the snap, so has cooled down a bit, but the temperature normally sits about the same place as yours, just above the 80º mark.

I always use S setting for the gearbox. Noticed yours is in C.
Might also be worthwhile giving it a dose of injector cleaner / fuel additive to see if that helps.

Anyway here's my reading for today, driving on local A & B roads and also country lanes, no m'ways and no dual carriage ways.....
I think the only way to get an accurate reading is to calculate it yourself.

Edit: P.S. Forgot to say, if you post up your VIN number someone will be able to check the data card regarding it having a DPF.

I wouldn't get anything like on such a short journey on the type of roads you describe - mine would be very low 40's at best.

I can get 50MPG on the display but to do that takes 100 miles of steady motorway driving. I wonder if the estates have a lower final drive than the saloons - mine is at about 2200RPM at 70MPH.

I reckon the trip computer reads a llittle high, but find it hard to check tank to tank as you can't tell if you're filling the tank to the same level.

Mine runs at 85C. I always drive in S mode too.


It's possible the OP could have something like a binding brake or wheel bearing. I also wonder whether injectors decrease in efficiency with age?

However I think driving style is likely to be the biggest factor - you sort of have to let it waft along, and take every opporunity to ease off the gas. Any form of "press on" driving style murders the MPG.

 

[naim22]

I wouldn't get anything like on such a short journey on the type of roads you describe - mine would be very low 40's at best.

I can get 50MPG on the display but to do that takes 100 miles of steady motorway driving. I wonder if the estates have a lower final drive than the saloons - mine is at about 2200RPM at 70MPH.

I reckon the trip computer reads a llittle high, but find it hard to check tank to tank as you can't tell if you're filling the tank to the same level.

Mine runs at 85C. I always drive in S mode too.


It's possible the OP could have something like a binding brake or wheel bearing. I also wonder whether injectors decrease in efficiency with age?

However I think driving style is likely to be the biggest factor - you sort of have to let it waft along, and take every opporunity to ease off the gas. Any form of "press on" driving style murders the MPG.

Is S mode better than C then? I would have though C would be more efficient but I guess I base this from E/S Switches in the older MB's where E was better.

I have noticed I have bearing noise so I presume a wheel bearing is on its way out, would this damage MPG all that greatly though? I guess these cars are very sensitive like earlier posters have said. The brakes are all OK.

Interestingly I did a throttle TCU reset today (to get rid of its London characteristics!) , and have immediately seen better results, not sure this is so much placebo, or down to the fact that I can seem to be able to tap the throttle so much lighter and the car reacts quicker and accelerates a bit quicker, It feels like improved throttle response meaning I feel like I dont have to push the pedal as much to get the car to move at roundabouts etc. (I even saw 47mpg out of the thing at one point today, wasnt long after a trip reset mind. It has settled more at 37/38 town driving which is way off before.)

The car has done 108,000 miles now so not huge mileage I'm told but there's no reason to believe the injectors haven't worn, like I said though the car has been maintained to a good standard.

Thanks ,everyone's feedback has been very helpful and appreciated. Makes me glad I joined this forum!

 

[azzyc200]

Is S mode better than C then? I would have though C would be more efficient but I guess I base this from E/S Switches in the older MB's where E was better.

I have noticed I have bearing noise so I presume a wheel bearing is on its way out, would this damage MPG all that greatly though? I guess these cars are very sensitive like earlier posters have said. The brakes are all OK.

Interestingly I did a throttle TCU reset today (to get rid of its London characteristics!) , and have immediately seen better results, not sure this is so much placebo, or down to the fact that I can seem to be able to tap the throttle so much lighter and the car reacts quicker and accelerates a bit quicker, It feels like improved throttle response meaning I feel like I dont have to push the pedal as much to get the car to move at roundabouts etc. (I even saw 47mpg out of the thing at one point today, wasnt long after a trip reset mind. It has settled more at 37/38 town driving which is way off before.)

The car has done 108,000 miles now so not huge mileage I'm told but there's no reason to believe the injectors haven't worn, like I said though the car has been maintained to a good standard.

Thanks ,everyone's feedback has been very helpful and appreciated. Makes me glad I joined this forum!

I have a c200 cdi and had same problem I used fuel and injector cleaner mixed it in my 20 pounds fuel and drove on motorway cleaning it out and power came back as normal, also I get 44mpg on a 5 pounds diesel, before I used to get 29 mpg so it makes a big different, change your diff and gearbox oil same time

 

[Rory]

Is S mode better than C then? I would have though C would be more efficient but I guess I base this from E/S Switches in the older MB's where E was better.

The most significant difference between C & S is that the car starts of in 2nd gear in C mode. I drive very gently, but even I find C mode makes the car a bit too dim-witted when pulling out of junctions etc. If you boot it, it'll shift down to 1st anyway, but it does it with an unseemly thump.

C mode would probably most benefit mid-speed rural driving, where the car will upshift a little earlier. Overall, C mode should be a little better on economy but the vast majority of my driving is on motorway, so it's not going to affect my MPG either way.

 

[V12]

Check tank to tank, ignore obc.
My S320cdi gets better figures. 50mpg is pretty easy if taking it steady on the motorway.

 

[naim22]

It's been a while but I have an update on this

Firstly my front tyre had a slow leak, this has now been rectified and helped a bit

However, I changed the thermostat and what a difference! Even though the car held temp in town, as soon as it got on a run it would settle between 70-80. The car also changes gear way smoother now too and sticks at 92 degrees solid. I can now see 50mpg if I CC at 60mph, 70 will give me like 44mpg and 80 about 40mpg which I think is reasonable

Thanks very much for all your help

 

[trapperjohn]

Thank you for the feed back and glad you got it sorted.