I expected more...........

[AMGeed]

MPG.

After selling the W212 E63 and replacing it with an S204 C180K Blue Efficiency, I expected a decent gain in fuel economy. It hasn't happened.
On getting the car on Sept 3rd, it was immediately obvious the thermostat was faulty, poor mpg and inefficient heater, so changed that out for a new Wahl thermostat and the mpg rose a bit and the heater works well.
But even on a run I'm only getting a maximum of 31/32mpg and I feel I should be in the 40+ region for a so called Blue Efficiency engine. I could squeeze 29mpg out of my 5.5l biturbo, so 31/32 out of a 1.6lt is pretty poor IMO. Around town its showing between 21 and 25mpg traffic dependant

Not sure what was done on the last service carried out by the main dealer last year, (its had an interim oil/filter change when I bought the car) but what could be causing such a poor MPG or is this what is expected from an M271 engine?

 

[Blobcat]

Tyre pressures low?
Super wide wheels?

 

[AMGeed]

Tyre pressures low?
Super wide wheels?

All good Russ.
Stock 17" rims with recommended tyre sizes too.

 

[Blobcat]

All good Russ.
Stock 17" rims with recommended tyre sizes too.

Perhaps it’s just small engine in a relatively heavy car and having to work too hard.

 

[sonic]

We had 2 SLK's a 2004 & a 2010 both with the M271 engine. 32/34 mpg was about as good as it got, did see 38mpg on some long runs.
The 350 mpg is only slightly less, not an economic engine.
We now have a SLC250d & are seeing 48mpg between services. If you keep it to 65/70mpg on the motorway it records 70mpg.

 

[Flyinspanner]

A small engine dragging around a ‘heavy’ car has to work harder.
(possibly exacerbated if you are used to a 6.3 and are keen to ‘make progress ).
Sometimes a 2L will give better mpg!

 

[malcolm E53 AMG]

Your figures are a bit on the low side according to Honest John but a lot depends on local traffic conditions

https://www.honestjohn.co.uk/realmpg/mercedes-benz/c-class-estate-2008

 

[alexanderfoti]

Our 200 Kompressor 203 is horrendous around town only just reaching 28mpg.

On a (looongg) run, I can eek 40+ mpg out of it, burs it's hard work

 

[AMGeed]

Hmm seems maybe my expectations were a little too high.
Makes me appreciate that Biturbo E63 even more.
Jeez I miss it

 

[alexanderfoti]

That said, you should be able to get better than 31mpg on a run. Mines the Kompressor, yours should be the turbo M271evo so should be more efficient.

 

[AMGeed]

That said, you should be able to get better than 31mpg on a run. Mines the Kompressor, yours should be the turbo M271evo so should be more efficient.

Mines a 2010 M271 Kompressor Alex

 

[alexanderfoti]

Still, I think if you cant push past 31 on a run, it warrants further investigation.

 

[AMGeed]

Still, I think if you cant push past 31 on a run, it warrants further investigation.

I'm thinking the same. I've not had it checked over by a MB specialist yet so perhaps now is the time. Shame you are so far away.

 

[alexanderfoti]

I'd start with the basics though, geometry, check tyres for rolling resistance rating and check the brakes for binding etc.

 

[Wighty]

I'm thinking the same. I've not had it checked over by a MB specialist yet so perhaps now is the time. Shame you are so far away.

I’ve the same engine on the CLK . Yes early 30’s for mixed running is about right . But a long motorway trip should at least be late 30’s .
What wheel sizes are you ?

 

[SL63 Mark]

Hmm seems maybe my expectations were a little too high.
Makes me appreciate that Biturbo E63 even more.
Jeez I miss it

My biturbo SL63 will do high 20s on a motorway run, but then it rarely revs over 1,100 RPM.

As a 2016 model, it has 900NM of torque at about 1,500 RPM (IRRC). This means it is rarely necessary to use many revs, just tickle the pedal, wait for the turbos to cut in, and enjoy the ride.

We have a 320d and an AMG for fun.

 

[C16RKC]

You need a Diesel!

 

[Wighty]

Two pics for you to peruse

 

[lewyboy]

I expected more.

Sounds just like my Wife.

 

[Judwin]

Quite surprised by these OM271 MPG reports.

Mines a facelift C180 W204, with the OM274 (1.6 turbo). Easily get 40+ MPG on a run of more than 10 miles, with a long term average of 42MPG over many thousand miles, and I don't usually hang about. Once saw 66MPG on a trip - but that was stuck behind a caravan on a single carrageway A road doing 50MPH for miles on end.

So I don't think small engine heavy car is very likely the problem.