I live in northern europe, Finland.
Interesting... and you're sure you've got a particulate requirement? I ask because if I take your argument as given, you've got the same engine as the Mercedes less the emmission equip in question yet you still pass emissions. This means that either:
1. your standard is differnet from the standard for which the Mercedes system was developed
or,
2. Mercedes has added cost for no reason
or,
3. you've misstated
or,
4. some combination of the above...
I think we can probably rule out #2 under Occam's razor. Trust me, this industry is quite sensitive to needless cost. Sometimes this leads to apparent paradoxes - like a wiring harness/loom that includes fittings for options you don't have. It's a cost of complexity save even as its partially offset with a material cost hit.
I'll see what I can find, as time permits.