The "real world" tests on 37 of the UK's most popular cars came after Volkswagen admitted using defeat devices to cheat emissions tests worldwide in September.
"It can be seen that all of the results are substantially higher than this limit, with the best results being about three times higher, and the worst about 10 times higher," read the report by the Department for Transport.
Vauxhall Insignias, Range Rover Sport and Nissan Qashqai were found to produce 10 times the legal limit for nitrogen dioxide levels when out on the road.
Peugeot 3008, Mercedes A180, and the Renault Megane all produced up to 12 times the legal limit.
But the car makers haven't done anything illegal because they only have to meet laboratory standards.
"The vehicles tested in the UK programme showed no evidence of car manufacturers, apart from VW Group, fitting devices to defeat the approved emissions test programme," the report said.
VW previously said 1.2m of its vehicles in Britain had been fitted with defeat devices.