Buyers guide w211 OM642 vs OM648

[hedzerd21]

I’ve been looking for a W211 E280/320cdi with either the 642 or 648 but I can’t make my mind up… One person says rhe 642 and 7g aren’t that good and that the 648 is more reliable and more economical, and someone else says the exact opposite… What are your personal experiences?
For me fuel economy is quite important, at the moment I’m doing about 35-40 MPG and I would’t want to go a lot lower than that, a bit is acceptable ofcourse. What would be my recommendation?

 

[Wighty]

We’ll post 2006 facelift are all newer cars which solved a lot of electrical problems and don’t have SBC problems .
ive had my E320cdi V6 for nearly 12 years by the way . 113k miles , no gearbox issues .

 

[hedzerd21]

We’ll post 2006 facelift are all newer cars which solved a lot of electrical problems and don’t have SBC problems .
ive had my E320cdi V6 for nearly 12 years by the way . 113k miles , no gearbox issues .

What mpg do you get under normal circumstances?

 

[s5tuart]

18mpg around town
38ish on a run for me in the CLS Shooting Brake
9g box

 

[00slk]

I went for the 320's as apposed to the smaller engine because the extra power is better, and to be honest all the 320's I have had have all done around the 35-40mpg for normal commuting. On a journey I get 45mpg from her.
I did once have a 240V6 petrol which was 26mpg average.
I have always gone for the bigger engine cars as I have found them better on fuel, except maybe the American cars I have had, they're shockers. Best I ever had from those was 22 mpg and that was on a long journey

 

[mioba]

The 642 is a design with some weak spots, orange seals should be service items and kept on top of, oil cooler seals are a weak point and an expensive plastic batwing air intake with inbuilt MAFS.
Ive never had an issue with my straight 6, 648.

As for economy I cant say as I have each engine in very different cars. But the straight 6 is smoother.

 

[hedzerd21]

The weird thing is, a few friends of me have the w204 c320cdi v6 diesels, but they can’t het above +-25 mpg with normal commuting…

 

[hedzerd21]

The 642 is a design with some weak spots, orange seals should be service items and kept on top of, oil cooler seals are a weak point and an expensive plastic batwing air intake with inbuilt MAFS.
Ive never had an issue with my straight 6, 648.

As for economy I cant say as I have each engine in very different cars. But the straight 6 is smoother.

what mpg are you getting with both cars?

 

[mioba]

what mpg are you getting with both cars?

Not relevant, as they are very different cars (weight)

in the W251 avg 26
in the W220 avg 34

you need to compare the engines in same model.

 

[hedzerd21]

Not relevant, as they are very different cars (weight)

in the W251 avg 26
in the W220 avg 34

you need to compare the engines in same model.

34 for a w220 is quite good imo

 

[M80]

If you want better economy the later OM646 is good.

 

[hedzerd21]

If you want better economy the later OM646 is good.

I would still rather have a 6 cilinder engine in an e class, as long as I’m not

 

[hedzerd21]

as long as i’m not getting any worse than +-32mpg*

 

[Wighty]

What mpg do you get under normal circumstances?

About 39mpg on long term mixed driving , probably late 40’s on a 300 mile cruise control motorway run .
For such powerful engines they shame a lot of modern smaller cars .

 

[Wighty]

The weird thing is, a few friends of me have the w204 c320cdi v6 diesels, but they can’t het above +-25 mpg with normal commuting…

Stop start slow stuff is not what this engine was made for .

 

[Uncle Benz]

OM648 in my S211 will do 37-38mpg on my 11 mile commute. It’ll go as high as 46mpg on a decent run. I have seen 50 on a couple of unusual occasions. In the winter my commute is a little worse, as the engine takes longer to warm up, about 10% worse. It’s a great engine, smooth as butter, no significant foibles. Fwiw I have an OM642 in my W164 ML. It’s a good engine, just not as good as the in line six imo.

 

[hedzerd21]

The only ‘problem’ I’m having right now is that I just like the Facelift more than pre facelift but it doesn’t come with an I6 engine… So is it worth it to take the V6 642 just so I can take the facelift version? I think I can get decent MPG because I’m not really a fast driver, I live in the Netherlands so I’m only allowed to drive 60…

 

[mersum1es]

My W220 OM648 did 8 L/100km, C219 OM642 is performing 8,5L/100km and w212 OM642 gets 7,3L/100km. Measured around year tank brim to brim.

 

[Hotspur]

E350CDI with OM642 - on a carefully driven run trying to get the best MPG for a test, I managed to get it to 60 but it wasn't easy to drive that economical for a prolonged period especially on roads with inclines - still a great engine with very good economy....and the engine, in fact the whole car has impeccable road manners, no matter what you ask it to do.

 

[Noddy 99]

E280 CDI Sport with 642 engine: I average about 34mpg but I tend to use my wife's Panda for any journey less than 10 miles...

Based on what I've heard about the general reliability of the cars, I would DEFINITELY go with the facelift - Mercedes made over 2000 changes to the model in 2006...