All cars tested by the Government following the Volkswagen diesel emissions scandal exceed laboratory limits for nitrogen oxide (NOx) when tested in real world conditions.
A Department for Transport report revealed that none of the 37 top-selling vehicles met the " real world"legal level of 180 mg/km.
Cars meeting Euro 5 standards - which could be sold up to September last year - were all "substantially higher" in real world conditions than measurements recorded in laboratories, according to the study.
The Vauxhall Insignia was the worst performer in the inquiry, emitting over 1,800 mg/km.
Even the best performer, the Citroen C4, was found to emit around three times the legal laboratory level.
Real world driving emissions tests will be introduced in 2017, although diesel cars will initially be allowed to pollute more than double the current legal level because of their limited ability to reduce real world emissions in the short term.
Cars that meet the current Euro 6 standards have to meet 80 mg/km NOx limits in laboratory tests, but in real-world driving for 90 minutes on normal roads the average level recorded was more than six times higher.
Volkswagen was forced to recall 8.5 million cars in October last year following revelations about the company rigging diesel emission figures.
The month before, VW admitted that 482,000 of its diesel vehicles in the US were fitted with defeat device software to switch engines to a cleaner mode when they were being tested for emissions.
But the Government's latest report found no evidence of car manufacturers, other than VV, fitting devices to cheat emissions tests.