Interesting indeed but it’s all very well using laboratory numbers for these sorts of things but they always miss the final link in the chain i.e. the driver.
I bet any money being a mature experience driver that the car I have causes less pollution than cars down the list that are driven by folk who have lead in the soles of their shoes and who jump on the brakes 20 metres from the stop line when the traffic lights are red or those driver that refuse to use stop and go.
What it tells us if we didn’t already know is the bigger the car the more pollution but like comparing a 5 Watt light bulb that uses less energy and therefore less polluting than a 3KWh Kettle but you can’t make a cup of tea with a 5 Watt light bulb.?