LONDON (Reuters) -- The UK government's transport ministry said all 37 car models it had tested exceeded the laboratory limits for polluting nitrogen oxides during real-world driving, but only Volkswagen had used so-called defeat devices to cheat tests.
The transport ministry examined cars from over 20 brands including Ford, VW, General Motors' Vauxhall and BMW. It tested 18 older cars against so-called Euro 5 standards for nitrogen oxide (NOx) levels and 19 newer ones against tougher Euro 6 levels, with all the vehicles recording readings above the legislative limit during on-road tests.
"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 ten times higher," it said, referring to vehicles tested against Euro 5 levels.
Transport minister Robert Goodwill said carmakers had "not done anything illegal" as they only had to meet laboratory standards at present but that real-world driving emissions tests would be introduced from 2017.
Among the older models, the Vauxhall Insignia midsize model recorded the highest NOx result of nearly 1900 mg/km, over 10 times the laboratory test limit whereas the Peugeot 3008 crossover had the highest emissions of the newer cars, almost 14 times the limit.
The UK launched an investigation into emissions after Volkswagen admitted to rigging U.S. diesel emissions tests in September.
The transport ministry said only VW had been found to be using defeat device software to cheat tests. "The vehicles tested in the UK program showed no evidence of car manufacturers, apart from VW Group, fitting devices to defeat the approved emissions test program," it said in a statement on Thursday.
- Download PDF of UK vehicle testing program results, above right
VW had previously said 1.2 million of its models in the UK had been fitted with defeat devices. It saw its UK sales plummet from October. They returned to growth in March, edging up 0.02 percent.
The ministry said it cost 1 million pounds ($1.4 million) to re-test the vehicles and that Germany would soon be publishing results of its own testing of 56 vehicles.
The UK's automotive industry body, the Society of Motor Manufacturers and Traders, said meeting real-world testing standards could be costly for automakers but that all models approved from next year will pass on-road tests.
"This will require significant additional investment by manufacturers but will add greater transparency so consumers can be more confident industry is delivering on air quality," a spokesman said.