An anonymous reader writes: Volkswagen has taken some serious heat for deliberately circumventing emissions tests with "defeat devices" in some of their vehicles. While no other cars have been found to use specific devices to fool tests in the same way, we're now learning that many manufacturers still mysteriously perform worse in the real world. Last week, the Guardian revealed that diesel cars from Nissan, Hyundai, Citroen, Fiat, Volvo, and Renault emitted significantly more pollution in realistic driving conditions than the tests supposedly allow. Now, we learn that vehicles from Mercedes-Benz, Honda, Mazda, and Mitsubishi emit substantially more than they should as well. For example: "Mercedes-Benz's diesel cars produced an average of 0.406g/km of NOx on the road, at least 2.2 times more than the official Euro 5 level and five times higher than the Euro 6 level. Honda's diesel cars emitted 0.484g/km of NOx on average, between 2.6 and six times the official levels." This provides clear evidence that the automotive industry is designing its cars to follow the letter of the law (passing tests), but not the spirit (actually reducing pollution).