C350 CDI om642 correct engine temperature?

[DSM10000]

The current cold weather will have an effect and with more load from lights, screen heater, heated seats etc
My W211 with an earlier version of the engine in your car averaged around 34mpg on mixed use. I did see 43mpg brim to brim on a 200 mile journey a few times.

 

[philnewmerc]

Good point. Temperature has plummeted since the thermostat replacement...

 

[DSM10000]

Good point. Temperature has plummeted since the thermostat replacement...

Plus you may have winter diesel in the tank which has a lower energy value due to the anti waxing additives

 

[E55BOF]

Three things to bear in mind: nobody ever attains the official test figures driving normally; Mercedes will have done everything they could get away with (make up your own mind whether 'Dieselgate' was actually out-and-out cheating, or just very sharp practice...) to minimize the fuel consumption on test; fuel consumption increases in winter.

I don't think you have a problem, and on a long motorway run you might well see 40 mpg at 70-75 mph. I would have in my remapped OM642 CLS 350 if I'd ever cruised at that speed...

 

[OneForTheRoad]

Not sure if you saw my mpg photo. Glc 350 4*4 . Over 281 miles sat at 65/75 mph I averaged 40.3 at best . Sometimes on cruise control.

 

[sautah]

I don't think you are driving far enough to get a decent MPG figure reading there. My 250 CDi can take an hour or more before it starts to read over 50 MPG especially after I have used it for some short runs or it's sat unused like over Christmas when I was away for 2 weeks holiday. In these instances it hovers around 38 ish.

As far as being 6 cylinder etc I also have a BMW 6 series diesel and that gets over 50 too on a decent run. Same issue though, You have to be on a proper run before it hits the 50+ mpg Driving it for 30 minutes or so just doesn't give it a chance.