E250 MPG Reducing?

[RavC]

Hello All,
I have a E250 2010 diesel with 160k on the clock, i've noticed its MPG has reduced from 47mpg to 36mpg over the past couple of weeks - any ideas to sort this out will be greatly appreciated.
Thanks
Rav

 

[ph47mf]

changed your driving style or been doing a lot of city driving?

The heat should actually make the MPG better

 

[RavC]

No, driving style is the same, combination of motorway and town miles!, foot has never been heavy! It is due for a service but will that have an appreciable difference?

 

[MercedesDriver]

I've noticed an improvement of few MPG since last month service with air filter change but your change is in a range of -20% which is a lot. What is the engine temperature reading? It might be running cold.

 

[RavC]

Sorry, temp has remained the same, tyre pressure is the same. Would the DPF filter affect performance?

 

[fabes]

might sound daft, but check your brakes

I only noticed I had a sticking brake calliper on our QQ when the MPG dropped
Front brakes being jammed on will affect MPG somewhat

and that is quite some drop .....

 

[RavC]

Sorry, silly question---How do i check them

 

[fabes]

Raise the wheel and spin it to see if it rotates freely or get to a garage who will whip the wheel off and be able to tell you
Front callipers seem to go more frequently than rear due to brake bias, so just the front wheels should allow you to disregard this as a reason.

You could even take advantage of a free brake check by Kwik Fit, (but you might not get an unbiased view given their sales based pitch, but then again, you might.....)

 

[Deleted member 65149]

I had the same sort of sudden drop in my C350 a couple of years ago. I had lots of suggestions as to the cause on here, but in the end it was resolved by an ECU and gearbox software reset. You can get this done at your MB dealer, an indie or google how to do it yourself.

 

[fabes]

I've got the same engine as you sir
What were the updates / what was explained to you as I am getting okay, but not impressive MPG from mine atm

(and I have checked my callipers....)

 

[RavC]

Went to Kwik Fit the other day, brakes are all fine tho rear coil have cracked! It's due in for a service on Tuesday so will speak to the guys and let them work their magic!!

 

[Deleted member 65149]

I spotted something interesting and puzzling over the weekend during a trip to London and back. The mpg was showing lower than I would expect on the obc trip digital display. But when I changed the display to show the sliding bar for instantaneous mpg, it was way better every time I glanced at it whilst on cruise control. Despite the instantaneous display mostly showing its max reading of 40mpg, the trip and mpg “scyscraper” display were both showing under 30mpg! The amount of fuel I used during the 200 mile round trip, much of it in heavy London traffic, was much more in line with what I would expect. The obc seems to be grossly misleading at random times - I think! I now have the choice of ignoring it in the future, or being totally obsessive and checking the mileage between full tanks of fuel.

 

[Black Scorpion]

The outside temp as the weather gets hotter will give lower mpg.
Aircon reduces mpg.
Hot roads and hotter tyres mean stickier grip so greater resistance and reduced mpg.
Turbo cars on hot days have reduced power due to intake temp so drivers need to push harder for the same power that is available on colder days.

 

[MercedesDriver]

The outside temp as the weather gets hotter will give lower mpg.
Aircon reduces mpg.
Hot roads and hotter tyres mean stickier grip so greater resistance and reduced mpg.
Turbo cars on hot days have reduced power due to intake temp so drivers need to push harder for the same power that is available on colder days.

So why then my MPG improves with temperature increment and I’m still driving with winter tyres?

 

[pmcgsmurf]

What's your engine temperature after fully up to temp?