How does that Mercedes naming work

[ELF]

Hey there.
I'm not a huge fan of Mercedes-Benz, but I have decided to model a danish emergency vehicle for doctors (They arrive along with ambulances to assist with pre-hopital procedures, and if special procedures are required at the scene of the accident). Now, at the website where they list all the emergency vehicles it says that they drive a Mercedes Benz ML-270 CDI, but on an unofficial site, it says a Mercedes Benz ML-350, and I can't find a Mercedes-Benz ML-270 CDI on MB's danish website.

Now, have I gotten this right... The ML-270 and ML-350 look the same, they are both part of the M-series, only difference is the size of the engine and maybe some of the equipment?

Also is the ML-270 CDI not listed on the official MB website, because it's out of production? So they might be driving, like, a 2003 make M-series, or what?

And does it matter? I found blueprints for both ML-270 and for M-series from 2005. Would it really make any difference in appearance/proportions, which I model from?

Here's a link to the Mercedes Benz ML-350 (The link to the official site with the 270 is in danish, and shows only a small picture):

http://www.112alarm.dk/ambulancelaege/laegeodense1.jpg

Thanks in advance, and sorry if I posted the wrong place, don't know where else to put it.