http://www.theguardian.com/world/2014/d ... pital-2020

I wonder how the car industry feels about that

I thought diesel cars produced less CO2 than petrol.
If not, why is my petrol car road tax so high compared to diesels.

I don't drive, but that had me wondering too.

Less CO2, more of other nasties.

Lots of nasty soot and other particulates - not good if you have a breathing condition. In the hot summers, it’s the diesel that causes problems in cities - hence the warnings to people with breathing problems not to go near central London. If Boris were to ban diesel cars, the taxi drives would be up in arms.

Car tax is based on CO2 output - it seems to ignore other nasties.

It is the micro particles that are the problem with diesel and a problem for asthma sufferers. That is why diesel is taxed much higher here - the fuel is cheaper, but the tax higher (10c a litre less than unleaded, but the tax is much higher, my Toyota Verso diesel cost 280€ a year in tax, my Citroen C3 costs 54€).

Obviously it isn't just diesel vs. petrol there, the Verso was a bigger car and it had a more powerful engine. That said, it was one of the cleanest vehicles at the time I bought it (2.2L D-CAT with 170ps), the Citroen is a 95bhp 1.4L petrol.

They say that you need to do over 20,000KM a year before diesel pays for itself (higher purchase price, higher tax but better consumption and lower fuel costs), comparing like-for-like (E.g. 2L petrol vs. 2L diesel in the same chasis).