I also heard this morning that the Lib Dems want all diesel sales banned by 2025, this just shows how uneducated they are, do they think petrol emissions are just harmless?! If they need to ban diesels by 2025 then they need to ban petrols too the Euro 6 emissions from a diesel is virtually identical to a Euro 6 petrol anyway!.
Petrol emissions are no where near as bad though, they don't have the cancer causing elements that diesels kick out. Nor anything like the level of NOX, which is 10x worse than co2.