I was thinking that way to be on slightly higher moral ground. I know my old petrol motor is a bit smoky but it's not the same stuff as comes out a diesel. Had a fellow park a newish diesel merc behind me as I was rigging up last summer, he kept the motor running to keep the AC going. They might pass the emissions test when brand new under lab conditions, but it's a rapid slide downhill once they leave the showroom.
www.theguardian.com/environment/2015/sep/22/the-rise-diesel-in-europe-impact-on-health-pollution"Diesel was a niche market in Europe until the mid-1990s, making up less than 10% of the car fleet. Diesels produce 15% less CO2 than petrol, but emit four times more nitrogen dioxide pollution (NO2) and 22 times more particulates - the tiny particles that penetrate the lungs, brain and heart.
Following the signing of the Kyoto protocol climate change agreement in 1997, most rich countries were legally obliged to reduce CO2 emissions by an average of 8% over 15 years.
Japanese and American car makers backed research into hybrid and electric cars, but the European commission was lobbied strongly by big German car makers BMW, Volkswagen and Daimler, to incentivise diesel. A switch to diesel was said by the industry to be a cheap and fast way to reduce the carbon emissions that drive climate change."