e320 cdi euro 3 vs euro 4 advice needed

[Fayiz]

Hey guys, I hope you're all well...

I know this has been asked quite alot over the years, especially on mb forums, but I'm still unable to receive the answer that I'm looking for...

Does anyone here know the exact differences between the Eu3 and Eu4 engines, for example the 2003 e320 cdi inline 6 eu3 and the 2004+ eu4 I know that the euro 4 is less economical, does anyone know the exact reason for this? For example, my old 53 plate e320 cdi was more economical than my current 04 plate e320 cdi by quite a significant amount... even though the 53 plate was an estate and the current car is a saloon... does anyone know what exactly was done which affected the economy? I have heard that there were many complaints regarding this, and that many early eu4 models (especially 04 plate) were remapped for this very reason... does this mean that I'd see a significant difference from a remap?

Any response will be much appreciated, thank you guys!

 

[malcolm E53 AMG]

I owned a EU3 OM613 for 14 years and sold it in 2019 and still miss that engine they are superb.

The reason why the EU4 OM648 is less economical is that it has a higher rated output at 204bhp (OM613 is 196bhp) with a variable geometry turbo and upgraded injectors and EGR. I could achieve a genuine high of 50mpg with the EU3 engine and I can get no where near that with my OM642 (V6) EU5 engine so some of the frugality of Mercedes Diesel engines has been sacrificed due to emission controls and increasing bhp to compensate along the way

 

[Fayiz]

I owned a EU3 OM613 for 14 years and sold it in 2019 and still miss that engine they are superb.

The reason why the EU4 OM648 is less economical is that it has a higher rated output at 204bhp (OM613 is 196bhp) with a variable geometry turbo and upgraded injectors and EGR. I could achieve a genuine high of 50mpg with the EU3 engine and I can get no where near that with my OM642 (V6) EU5 engine so some of the frugality of Mercedes Diesel engines has been sacrificed due to emission controls and increasing bhp to compensate along the way

Cheers mate...

I was more curious in terms of why the Om648 eu3 and eu4 are much different in terms of economy though, they're both 204 bhp etc... But both have a significant difference when it comes to mpg..

 

[malcolm E53 AMG]

I thought the OM648 was manufactured in EU4 guise only, if not I’ve learned something?

 

[Fayiz]

Ah no, there were 2 versions mate, the euro 3 was in place until 2004... You can tell the difference by the engine covers, the silver and black cover = euro 3 and the full black cover on the 04 plates onwards is euro 4...