Volkswagen scandal triggers hunt for political responsibility

"The government told us in July that it knew about this software, which has been used in the USA. It's clear they knew the software was widely in use", Krischer, of the Green party, told N24 television. He said he was "surprised with [transport minister] Dobrindt's surprise".

Dobrindt denied the suggestion that the government was aware of the scheme.

Meanwhile, the Guardian reported on Thursday that Germany, France, and the UK have been lobbying to maintain loopholes in car tests.

The report said that according to leaked documents, the EU's three largest countries tried to persuade the EU Commission to keep certain characteristics of an old emissions testing system in the World Light Vehicles Test Procedure (WLTP) which is supposed to replace it.

The WLTP is aimed at reducing the disparity between measured greenhouse gas and pollutant emissions during car tests, and actual emissions when driving.

Greenhouse gases contribute to potentially catastrophic climate change, while pollutants decrease air quality. According to estimates, 40,000 Europeans die prematurely every year because of air pollution.

According to NGO Transport & Environment, the discrepancy between measured and actual emissions is 40 percent, and the Volkswagen scandal is just the "tip of the iceberg". The NGO called for an improved testing system in the EU.

It said "the European system of testing is much less independent and robust than that in the US where 10-15% of new models are retested by the US authorities in their own laboratories".

"In Europe, carmakers pay certified testing organisations to perform tests in the carmakers' own laboratories. … But carmakers 'shop' for the best deal from agencies across Europe and directly pay for their services", the NGO said in a statement.

MEPs also discussed the matter on Wednesday and told the Commission they were worried that other carmakers may also have used similar cheating methods.

Liberal MEP Nils Torvalds noted that the EU could have improved its testing system a while ago.

"This is a scandal, and a grave scandal, but at the same time we must look ourselves in the mirror and see what we have achieved in the past couple of years and realise that we have missed opportunities to improve testing and thereby to reduce car pollution", he said according to a press statement.

The EP's environment committee on Wednesday also voted to ask "real world testing" to be introduced by 2017.

Meanwhile Volkswagen CEO Winterkorn said he was "not aware of any wrongdoing on my part". However, after mounting pressure Winterkorn resigned.

"Volkswagen needs a fresh start, also in terms of personnel. I am clearing the way for this fresh start with my resignation", he said.