The plate was the first it was import (being a relatively recently issued plate on an older car) & the plate frame comes from "Mercedes Benz Rhein-Ruhr" which has locations in both Düsseldorf & Duisberg, Germany
In Portugal it's very hard to find low KM w211, even harder if you want it fully equiped like this one seems to be. The only way is to import it.
In 2023 I was about to do the same on a w211 from switzerland. I waited months trying to find a decent w211 but none appeared on the market. Ended up buying another type of car since legalizing big engine was gonna be expensive, plus I would have to pay modern IUC prices for a big engine yearly.