Looks like the electric car agenda. Basically the governments want us to drive electic cars so they demonise everything around diesel. My take would be the car companies lobbied (lobby means bribe) the governments to pass these tests in the past. Now it's dirty diesel, gotta tax them more because they cause cancer ect (they probably knew this anyway).
Now why would they want us in electric cars? Diesel and petrol hybrids are most likely as green if not greener than electric cars. I'm not mad, you need to produce the electricity somewhere using something if your to power the car. Not only this but you have to have a constant electric supply in the power grid whereas motor cars produce power when needed and use zero power whilst not in use. So back to the question. I think it's simple. It's easier to control you/us if we depend on electric. Im gonna leave this here cause my truth seeker characteristic is starting to flow too much, that or I am indeed mad.