• The Forums are now open to new registrations, adverts are also being de-tuned.

E280 W211 MPG

RidleyRumpus

Member
Joined
Nov 8, 2019
Messages
51
Location
Essex
Car
E280
I have had my E280 for a few months now and it is a really nice car.

Just one question, when I got it I was getting 48MPG on a run but now I am only getting 38MPG.

What do you reckon has changed so much in a couple of months?
 
It is now colder, diesels are less efficient when cold and take longer to warm up than petrol engines. I assume you are driving on the same roads etc as when you recorded the lower consumption?

Also, what is the water temperature after 20 miles or so of driving? Thermostat failure is not uncommon and can lead to increased fuel consumption.
 
Water temp seems fine

Warming up should not be a problem as we are talking 100+ mile journeys on motorways.
 
Water temp seems fine

Warming up should not be a problem as we are talking 100+ mile journeys on motorways.

Yes but the 38mpg is an average of that trip, if it is taking longer to warm up initially that will affect the average. Have you tried doing a brim to brim calculation? The trip meter fuel read out is not that accurate

Water temperature should be around 85 - 90 Deg C fully warmed up
 
Yes but the 38mpg is an average of that trip, if it is taking longer to warm up initially that will affect the average. Have you tried doing a brim to brim calculation? The trip meter fuel read out is not that accurate

Water temperature should be around 85 - 90 Deg C fully warmed up

Brim to Brim was slightly lower than the trip meter showed. I will check the way the water temp rises but it has seemed to rise pretty quick.
 
My E280 will usually do about 43-45 mpg on a long run mostly on the motorway, and it did once manage 50 mpg which I put down to long stretches of 50 mph average speed zones through roadworks. I do not find that the cold weather affects mpg very much on my long runs, but when my economy drops it is usually dirty filters or in need of some Redex; the latter I now use regularly because the supermarket fuel I use has no cleaning additives to speak of.

Out of interest, when were the filters last changed and do you use supermarket fuel?
 
Colder weather will see a drop in MPG, Also maybe worth while changing the Fuel filter
 
Brim to Brim was slightly lower than the trip meter showed.

I've yet to learn of a fuel trip computer understating the actual situation.

I guess when the manufacturers are allowed to produce the thing that tells the customer how good their vehicle is on fuel, it's perhaps no surprise it overstates the position by 10% > 20%.

It's not like they try any trick in the book to make their vehicles appear to have better economy than they actually have! :D
 
I've yet to learn of a fuel trip computer understating the actual situation.

I guess when the manufacturers are allowed to produce the thing that tells the customer how good their vehicle is on fuel, it's perhaps no surprise it overstates the position by 10% > 20%.

It's not like they try any trick in the book to make their vehicles appear to have better economy than they actually have! :D


To be fair it must be incredible difficult to instantaneously measure that tiny amount of fuel being transferred.

That being said it is remarkable that they always err on the optimistic side....;)
 
My E280 will usually do about 43-45 mpg on a long run mostly on the motorway, and it did once manage 50 mpg which I put down to long stretches of 50 mph average speed zones through roadworks. I do not find that the cold weather affects mpg very much on my long runs, but when my economy drops it is usually dirty filters or in need of some Redex; the latter I now use regularly because the supermarket fuel I use has no cleaning additives to speak of.

Out of interest, when were the filters last changed and do you use supermarket fuel?

Yes I have been using Supermarket fuel and I have not changed the filters since I got the car. I believe it has a FSH and was certainly on a MB service plan since new.
 
Drop in temperatures and a switch to winter diesel would be my assumption.
 
Yes I have been using Supermarket fuel and I have not changed the filters since I got the car. I believe it has a FSH and was certainly on a MB service plan since new.
When I say I haven't changed them since I got the car we are talking a couple of months and 2-3k Miles
 
There are several factors that will increase fuel consumption in colder temperatures.

For motorway driving by far the biggest effect is increase in air density which produces a proportional increase in aerodynamic drag. A 20 C drop in temperature will increase drag by 7.4 % and as most of the power consumed at 70mph is due to drag so the mpg reduction will be most of that 7.4 %. This is a much bigger effect than the other possible cold temperature factors such as the lower calorific value of winter fuel and uncorrected lower tyre pressures.
 

Users who are viewing this thread

Back
Top Bottom