[UFO]

I've had a little trouble putting the scale of the pollution into perspective, but I suspect the actual pollution is still less than earlier VW designs. Compared to a gasoline vehicle, diesels emit less of most pollutants, but do put out more NOx due to the nature of the engine having higher combustion temperatures. This results in better mileage, but also more oxides of nitrogen, which is difficult to scrub. I also suspect it is easier for diesel engine manufacturers to prevent the formation of NOx rather than treat the exhaust, but that comes at the expense of engine performance.

Obviously VW was wrong to cheat the system, but it gave them an advantage in the diesel market. Everyone else had to put in NOx pollution scrubbers, and VW avoided much of that.