Unfortunately the marketing for diesel cars, at least in Europe, failed to sell the point of the diesel car, hence a bunch of eejits deciding that illegally removing the particle filter would be a good idea: Diesel cars are great for long journeys! If you use them to go to the shop, never exceeding 60km/h and with the engine barely reaching the optimum temperature, it'll clog the particle filter on the long run. But no, people still were following the other sheep because "diesel is better" (which is debatable, depending on your usage pattern of a car).
As for unreliable test results, VW scandal aside, there's been plenty of news around that auto car makers do cheat on those to get better figures: over-inflated tires, cars somehow stripped down of normal components/features, duct tape covering panel gaps, etc. The testing standard is really not the best. My suggestion: do a 5 minute drive on all the different speed limits of your country/location/state, with a standard version of a car. Calculate the average between all the different limits, voila?
