Have you ever had the DPF replaced? On most diesels they get so clogged up after around 150,000km so that the engine can't work efficiently anymore (and it can actually break the engine if it gets clogged enough).
You can pay to have it replaced (a few thousand Euro) or in a lot of countries it's quite popular to just remove the guts of it, so the there is no filter, meaning your polluting car pollutes even more. It's usually illegal, but as particulate emissions are not part of periodic inspection most European vehicles undergo, it's usually not found out.
(They weren't required until Euro 5 came into affect, so maybe your car doesn't even have one.)
You can pay to have it replaced (a few thousand Euro) or in a lot of countries it's quite popular to just remove the guts of it, so the there is no filter, meaning your polluting car pollutes even more. It's usually illegal, but as particulate emissions are not part of periodic inspection most European vehicles undergo, it's usually not found out.
(They weren't required until Euro 5 came into affect, so maybe your car doesn't even have one.)