CLS350CDI Shooting Brake.
Getting a real 29.3mpg average across 8785 miles in all conditions since I got it last Feb. All fuel and mileage tracked.
Motorway is better but actually not by that much. Get about 36mpg out of a trip oop North with the cruise on at +20.
The computer tells me over 40mpg but clearly that is not a true figure.
I was getting almost exactly the same economy out of my old 2002 S210 E320CDI estate so I'm not exactly impressed with the fuel economy improvements in the last 11 years.
Not surprised at that at all, my E350cdi estate used to lie as badly.
My E350 3.5 petrol however is actually under reading, oh, and now I have done 40k miles in it it is averaging 3mpg behind the diesel, with an average of 29.7mpg calculated.
I have a theory!! Haha
No, seriously, I reckon it is all about where the OBC starts off from cold, the E350cdi used to start at 40mpg and slowly climb down and then slowly climbs up if I did more than 15 miles or so.
Where as the petrel starts at 14mpg, sits there for around a mile or two and then slowly creeps up.
My theory is 14mpg from cold is probably a little low for the petrol, where as 40mpg from the 350cdi from cold is wildly optimistic.
As many of the journeys I do are sub 15 miles, which is where the 350cdi starts to creep up again, this means most of the journeys are well out on the OBC.
I have seen it with many petrol and diesel cars now, 330i vs 330d, 530i vs 530d, 335i vs 535d, A6 3.0tdi vs 3.2fsi and they all do the same.
I suppose they have to work out an average owners average journey length to get it nearer the truth, but I reckon far more people do sub 10 mile journeys for 80% of the time then they do 20+ mile journeys.
If the computer started at 29mpg from cold on the 350cdi I think the OBC would be much more accurate for many more owners.