I have just sold a 2.0litre diesel peugeot and bought my first Mercedes C220 diesel (2006, automatic, estate). The Peugeot turned 47mpg driven sensibly so imagin my disapointment at getting less than 30mpg from a similar size engine in the merc. I have driven it nicely, pumped the tyres up to max (to reduce roling friction), kept the aircon / heated seats off to try to improve economy. I am a degree qualified engineer but fail to see what Mercedes have done to make the fuel economy so poor. Can anyone offer an explanation? Does having 245x40x17inch wheels really produce that much more rolling friction? does bypassing the EGR make any difference and does removing the cat/particulte filter help. (Removing the cat and EGR lifted the Peugeots mpg from 44 to 47!)
Answers / discussion welcome as I will not be able to afford to run it in UK ($7.5 per USgall).

 

So with lots of people reading and no answers I assume everybody is too busy blinging up the cars to care about fuel economy. What have Volkswagen done to make their similar sized passat do 56mpg (recently confirmed by a friend of mine) that Mercedes have not? (Thats 56 miles per imperial gallon not US gallon). If the C220's 5speed auto gearbox has a torque converter "lock up" in 5th gear to reduce losses then the auto vs manual argument is lost as the transmissions are equal. That leaves aerodynamics, engine efficiency and car efficiency. A C220 is about as aerodynamic as you can get and my guess is that it has the same coefficient of drag as a passat. So its down to the merc having bigger tyres and the mercs enging being less efficient.
Answers on a post card.....

 

Mercedes is not known for the best fuel economy in any of the same engine class compare to other vehicles. Peugeot is not as heavy and the auto tranny will add to fuel cost in petrol and diesel vehicles.
My boss has a diesel passat for about 3 years now, I believe manual transmission, everaging 47-48 mpg (US gallon but also he drives like an old lady).
Check and replace your air filter, if it is dirty.
Bernard

 

stange you only get 30 mpg out of the C220 while even the ones form the 80s easily attain that without givin up aircon, and throwing everything out except a milkcrate to sit on.
For someone in the market for a fuel miser car, Mercedes usually aint top choice. They are about the heaviest in all it's relative classes, they have more moving parts and more elecronics, and modules than a NASA shuttle, especially the new ones, and when bought brand new for the price, not many people see fuel as that much big of a concern.

For example even the newest 4 door Rolls Bentley manage to get 9 and 12 and no one cries foul. Even the V-12 benz manage around 19-20 on the highway but the rolls is heavier, and fuel economy was not priority when built as such saying a car built and engineered for pure fuel econmy like the small eco boxes that loose 10-2% of their MPG just because AC and you might see 60 mph before you kick bucket.

It's not that the Mercedes engines are "less" efficient. It's just their efficentcy is focused somewhere else. Performance, smoothness, while giving decen mpg. Prius focus is fuel economy and everything else is third class citizen. Ferrari's is performance and it will drink gas by the gallons in one lap of a track. Efficiency all depends on what the prupose is. The Mercedes is one of the most efficient cars when it comes to doing what it was meant to do as is the Prius and Ferrari. They each have different purpose. If fuel econ is number one, then there are better choices than a Mercedes. If pure in your face heard foru miles away performance is the priority then Mercedes is again wrong choice. If a mixture of pure plush, luxury, good performance, quiet, refinement, decent gas mileage, then there is really no beating a Mercedes in any class from C-class to S-Class to Maybach.

 

and by the way the peugeot is not bad of a car. I like the 505s of the 80s. Just hate manual trannies and thus not many 505s to be found and even less with an automatic.

 

Hey guys , i have a 05 c230 k , as u may know there are two modes to drive this car C confort driving and S sport standard driving . C mode starts with the second gear and S starts with the first gear . My question is ,which mode is more fuel economy . thx

 

either one can be, but it's usually easer to maintain better smoother and lower rpms with comfort mode. Sports mode tends to delay shifts for better performance, which means higher rpms on average than comfort mode.

Overall the difference is miniscule andstill depends mostly on the driver style f driving. If you floor it on even comfort mode, more than likely the car will down shift anyways and still use up more gas while in sports you;ll get a slihtly quicker response because there is no down shift but the fuel economy is about the same when measured for extended amounts of time, now in some cars sports mode also cuts out overdrive which in that case, Comfort mode is more economical for long driving. In some cars these day overdrive is still present even in sports mode, just that it used for quicker throttle response and as an answer to the manual transmission's so called performance advantage. (in the hands of a good driver manual tranny can inprove performance but your average smoe joe cannot operate the gears effeciently enough and identify proper shift point to use that advantage compared to modern automatics.)