Diesel hybrid emissions

One of the interesting points hidden away in Which's revelation was that:

"95% of diesel cars, along with 10% of petrol cars, pump out more NOx than EU limits allow",

was that one diesel hybrid was exceeding the EU limit by up to 3 times.

If we are serious about tackling air quality problems should we be focussing on promoting and purchasing the following vehicle types:

Electric, electric hybrid, biomethane / CNG, hydrogen and (in terms of particulate and NOx emissions) Euro 6 petrol (with some exceptions)

and discouraging all diesels (including hybrid and Euro 6) and older petrol vehicles?

I'd welcome your views.