I get the idea behind smaller IC engines but Governments of all persuasions are paying lip service to climate change/pollution. Why do they still allow all the plumes of smoke and flames as footballers, rugby teams run out, score a goal/try. Firework displays for special events/new year and thousands of other situations all contribute to climate change and pollution yet they want to ban diesel cars. Perhaps they should start to cut down on industry, air travel, dirty buses and trucks.
It's worth putting some numbers on it, I think.
Then breaking down the "transport" slice of the pie:

