W212 E220 CDI-Poor economy

[masaeb]

Hi,

I've had a W212 E220 CDI from new for the last 3 years, and have currently done 25,000 miles.

The car is mostly used for doing the school run and town driving with the odd run on the dual carriage way.

Despite our best efforts the average economy sits at around 22 to 25 mpg, which is just dire.

Whilst I appreciate the claimed 40+ odd mpg for town maybe be far fetched, I would have thought I could at least get to 30 mpg.

I took the car to the dealer a while back but they found no faults...anyone idea's how to fix this?

Thanks

 

[DSM10000]

Are you sure there is something to fix?

Short runs where the engine is never getting up to optimum temperature will give poor fuel consumption figures. Diesels are not going to offer the best consumption figures in these conditions

Presumably you have checked for correct tyre pressures, wheel alignment, dragging brakes etc?

What is the engine water temperature after one of your normal drives? Does the water temperature get to around 90 Degrees C after a long run?

 

[Red C220]

Diesels don't like lots of short runs, it's only once warmed up and on a open road that the economy really kicks in.

I don't commute but I still manage around 18,000 miles a year in our cars. Not much of which is motorway - my real world measured average is below in my signature. It's an E220 CDI 2014

The telltale here is you've done 25,000 miles in 3 years - an average of 8,000, much of which is short school run trips. So a large proportion of the 8000 miles is spent warming up a cold engine block.

Bottom line is you need a petrol and it will probably do a similar figure, if not even slightly better.

 

[Deleted member 113659]

Wowzers!

Not good news to me having just ordered this very car and handing a B Class back that's covered 16,000 miles in 3 1/2 years

So just 4500 mile pa for us. Hope deisel stays at 98p a litre for the next 2 years!

Ant.

 

[masaeb]

Are you sure there is something to fix?

Short runs where the engine is never getting up to optimum temperature will give poor fuel consumption figures. Diesels are not going to offer the best consumption figures in these conditions

Presumably you have checked for correct tyre pressures, wheel alignment, dragging brakes etc?

What is the engine water temperature after one of your normal drives? Does the water temperature get to around 90 Degrees C after a long run?

-Hi, thanks for taking the time to reply, just had brand new discs, pads and tyres, still the same- temp gets just over 80 degrees.

I was thinking to get an eco remap from GAD Tuning....

 

[masaeb]

Hey, thanks for your posts...I think Petrol is the way forward

 

[paul_f]

Diesels don't like lots of short runs,

No internal combustion car likes short runs. Electric cars are perfect for short runs!

Bottom line is you need a petrol and it will probably do a similar figure, if not even slightly better.

A petrol in the same size car will probably do worse on the same drive cycles. It is still a very heavy car.

My wife's 1.6 petrol small Nissan only averages 28mpg doing similar short journeys

 

[Red C220]

No internal combustion car likes short runs. Electric cars are perfect for short runs!




A petrol in the same size car will probably do worse on the same drive cycles. It is still a very heavy car.

My wife's 1.6 petrol small Nissan only averages 28mpg doing similar short journeys

What's the electric equivalent to an E class?

 

[DSM10000]

-Hi, thanks for taking the time to reply, just had brand new discs, pads and tyres, still the same- temp gets just over 80 degrees.

I was thinking to get an eco remap from GAD Tuning....

When you say the temperature gets to just over 80 degrees, how long have you been driving before this is reached? It should get closer to 90 degrees C when fully warmed up. A faulty thermostat will increase fuel consumption.

 

[Trickythemerc]

My 220 CDI will show 80c after about 2.5 miles but a diesel needs a lot longer to get up to the optimum working temp probably more like ten miles before the whole lump is up to temp. They need long runs and often,mine averages 36 round town and anything up to 47 on a good run.

 

[masaeb]

When you say the temperature gets to just over 80 degrees, how long have you been driving before this is reached? It should get closer to 90 degrees C when fully warmed up. A faulty thermostat will increase fuel consumption.

It warms up pretty quick, its a 5-6 minute drive in the morning, I will check tomorrow and check it properly, thanks.

 

[masaeb]

Theres a Hybrid 5 Series, and there was there E300 Bluetec with the diesel and electric engine....should have gone for that!

 

[masaeb]

When you say the temperature gets to just over 80 degrees, how long have you been driving before this is reached? It should get closer to 90 degrees C when fully warmed up. A faulty thermostat will increase fuel consumption.

Did the school run this morning, mind it was very cold, about 2 degrees outside, a 10 minute drive, car only got up to around 50 degrees, got about 15 MPG...

 

[DSM10000]

Did the school run this morning, mind it was very cold, about 2 degrees outside, a 10 minute drive, car only got up to around 50 degrees, got about 15 MPG...

10 minutes driving starting from below 0 degrees OAT will, as you have discovered, hardly warm the engine.

You need to take it on a longer run, 20 miles or so at motorway / dual carriageway speeds and then see what the engine coolant temperature is.

It is possible you have faulty thermostat but you need to establish the running temperature of a fully warmed up system first.

As for the displayed MPG, MB systems are slow to re-set, if you re-set manually after half the journey you may well see a higher figure displayed.

Of course the only way to accurately determine fuel consumption is to carry out a number of brim to brim tank re-fills and work it out from there.

 

[masaeb]

10 minutes driving starting from below 0 degrees OAT will, as you have discovered, hardly warm the engine.

You need to take it on a longer run, 20 miles or so at motorway / dual carriageway speeds and then see what the engine coolant temperature is.

It is possible you have faulty thermostat but you need to establish the running temperature of a fully warmed up system first.

As for the displayed MPG, MB systems are slow to re-set, if you re-set manually after half the journey you may well see a higher figure displayed.

Of course the only way to accurately determine fuel consumption is to carry out a number of brim to brim tank re-fills and work it out from there.

Hi, so on Friday I made a series of short journies and kept resetting the trip meter once the car warmed up.

1 Mile, 5 mins, temp stayed at 40 deg, 15 mpg
1 mile, 5 mins, temp at 40, 22 mpg
1 mile, 5 mins, temp at 50, 17 mpg
1 mile, 5 mins, temp at 80, 32 mpg
1 mile, 5 mins, temp at 80, 29 mpg
1 mile, 5 mins, temp at 80, 31 mpg

On the weekend on a longer run, it took 15 minutes to get to around 80 degrees, at which point I parked the car and then at idle it took another 10 minutes to get to 90, after which point when I drove I started to see MPG in the high 30's and 40's for the rest of the day.

I have an MOT on friday so I will tell mercedes to have a look.

Thanks for your help.

 

[kid-jensen]

Depressingly, your figures point to there being nothing wrong but the length of your journeys..

Can't you walk the 1 mile journey and do the environment a few favours?

 

[Jim55]

Yeah ,1 mile is in no way enough

After heating up properly to around 90 u said u got 30-40 , so there's ur answer , get it warm and it works better

 

[190]

I do a 4 mile commute and consider even that distance as abusive use for any vehicle. Even if the engine just about reaches coolant temperature the oil most certainly doesn't and that's what counts especially in the winter. I can't walk that far on a regular basis and therefore choose the lesser of two evils by abusing my motorcycle engine rather than the car. It's an order of magnitude easier and cheaper to fix if it's ever needed.

 

[Dinnie]

Even with the car up to temperature and you did another 1 mile with the computer reset, you were probably accelerating and de-accelerating in that time a lot. If you were doing a constant 30/40/50 mph then you should see a lot better mpg.

 

[StuartK]

Hi,

I've had a W212 E220 CDI from new for the last 3 years, and have currently done 25,000 miles.

The car is mostly used for doing the school run and town driving with the odd run on the dual carriage way.

Despite our best efforts the average economy sits at around 22 to 25 mpg, which is just dire.

Whilst I appreciate the claimed 40+ odd mpg for town maybe be far fetched, I would have thought I could at least get to 30 mpg.

I took the car to the dealer a while back but they found no faults...anyone idea's how to fix this?

Thanks

I can get 25 out of my c63 driven carefully that's appalling for a diesel