Fuel consumption

[tfb]

hmmmm...I am really quite suprised by some of the MPG figures being quoted, I thought that the CDI engines were a lot better than that.
I drive up and down the A1 between Peterborough and London and can usually get 26MPG out of my 420SEC and when I use the wife's petrol BMW 528 estate I can easily get 35MPG and by really trying I have even had it up to 38MPG one time.

Regards

TFB

 

[Chris-net]

many thanks for all your reply's.
i've read all 17 pages on the merc owners forum here & this is what i've gleaned:
merc added a particle filter in 2004 to meet EU4 regs in the 200/220 engine, which reduced fuel economy.
EU4 engines use different oil from EU3 engines
some early EU4 220's where 143ps the rest are 150ps
the particle filter gets coated in soot and the car needs a good thrashing to remove the soot. is it best to do this with a cold or hot engine? should i leave the car in neutral and rev it or whilst driving, get the auto box to go to the lowest gear and floor it?
in top gear, 2000 revs is about 60mph whilst cruising and about 2200 when accelerating.
my car appears to not go into overdrive or even the highest gear especially when travelling at 30 mph and never with cruise or speed limiter on. i've noticed that whilst driving in d if i knock the lever to the right the car will go into the next gear sooner so i can take more advantage of the in gear torque available (i would expect the auto box to move to the most economical gear available asap)

i reset the last reset trip when i last filled up & will check milage/litres used when i fill up tomorrow.
i drove to bexhill on boxing day ~110 miles mainly duel cariagway and motorway at ~80mph and averaged 34 mpg. on the way back yesterday i averaged 38mpg at ~80mph pulling the gear lever to the right when i wanted a higher gear and flooring it every so often to try and clear the filter.

the car goes in for service in 2 weeks & had my comments added to the work sheet for the mechanics to investigate.
I'm considering writing to Merc to see if there's anything they can do as 34-38mpg on long motorway journeys isn't very good especially in a diesel. i got 44mpg out of my golf gti 1.8t in the scottish highlands (i was being especially good though)

 

[Blobcat]

Hi & Welcome

The particular filter should clear itself by using some extra fuel. This is why the Eu4 engines initially had worse fuel economy than Eu3. There was an MB update though which should have corrected the fuel economy.
Is yours a C or an E and what age? A colleague of mine used to see >50mpg regularly on his W210 220CDI. My W210 320CDI shows >40Mpg on the trip computer for the average so yours is not running well at all.

 

[Chris-net]

many thanks Blobcat,
mines a c220 registered 11/11/04. it had its first service 2 weeks after i bought it (paid for by merc) and they did some recall and warranty work on it including replacing the particle filter, updating the gearbox software and changing the engine oil. the new oil is meant to extend the service interval but its only given me 10kmiles.
do you know how long it used the extra fuel to clear itself (entire journey or a few mins?)
how do i find the 'w' desgination for my car?

 

[Blobcat]

First 3 Number of your Vin = the model, then a W for Saloon and S for Estate

The ASSYST system needs to be programmed that it has long life (Mobil 1) MB Specification oil. Once it has this it 'should' sit at 13K to next service then depending upon how your drive count down slowly until ~18K miles before next service. However the newer ASSYST systems don't always follow this :-(

I believe (although don't know for sure) that the car decides itself when to clear out the particular filter depending upon some sensor or other.

 

[psmart]

Back again! and this post took my interest, because the same has happened to our C220cdi.

It is a C220cdi Sequentronic from mid 2002 and in the first 3 years we used to get excellent economy, best achieved was 66mpg on a drive to Man Airport. We find the Sequentronic program will always stay in a lower gear than it should, so these figures are based on tiptronicing it into the gear it should be in.

The car is now 27K and 4 years old and we are getting sub 40mpg! Ive plugged the diagnostic computer in, and nothing is being reported as faulty. Admittedly, it is mainly driven by old codgers, but I make a point of thrashing it when I get in, ie. 140mph on the Yorkshire Moors
I was going to swap the oil for Lucas 0/40W fully synthetic, to see if this helped, but the drain plug is a sod to get to on these cars and sucking out oil when there is no dipstick is darn difficult. I mention this, as I put 0/40W fully synth in my ML and the economy is better.

I dont have any time at the mo (hence not being on the forum as much as I want), so any light shed as to why (Ive done the usual, such as cleaned airfilter, run injector cleaner through it, verified injector/bar pressures etc). Any help out there? OR IS THIS A CASE OF MICROSOFT, PROGRAM CARS TO STOP GIVING DECENT ECONOMY SO YOUR FORCED TO UPGRADE