Originally Posted by maswastage
Emissions regulations in the US are more stringent when it comes to particulate and nitrogen emissions, two areas where diesels traditionally do worse than gasoline engines. The Diesel Particulate Filter in modern diesels allows them to comply with regulations when it comes to particulates, and urea exhaust injection allows them to comply with nitrogen emissions regulations. The problem is fitting the vehicles with these systems and making it cost effective, but that's a challenge I think BMW is more than capable of meeting.
I get it now - a bit of nitrogen from the tail pipe of diesel is much more harmful than all the pollution that comes from banning diesel and having most punters drive 20mpg petrol cars.
Glad big oil lobbyists cleared that up for you!