The idea - still very much just a notion - would limit speeds on the country's highways to 80 mph. Proponents say this would reduce air pollution, help fight climate change and reduce the number of car accidents.

Chancellor Angela Merkel's spokesman, Steffen Seibert sought to smooth the waves created by the leaked report, saying on Monday that a government-appointed committee examining various proposal isn't finished yet. 

Germany could be hit with heavy EU fines if it fails to reduce emissions of greenhouse gases and poisonous nitrogen oxides. 

Transport emissions, which have not fallen since 1990, are a particular target for reductions.

The government is torn between the need to protect Germany's crucial car industry, buffeted by a series of costly emissions cheating scandals in recent years, and the need to act to protect a rapidly deteriorating climate.

The paper says measures including a motorway speed limit of 130 kmh and fuel tax hikes from 2023, the abolition of tax breaks for diesel cars and quotas for electric and hybrid car sales could deliver half the greenhouse gas emissions cuts that are needed.

The National Platform on the Future of Mobility has yet to finalise the recommendations. It is due to report its findings at the end of March, which will then be incorporated into a climate change law the government wants to enact this year.

But the committee is well aware that many of its suggestions could be controversial.

'Not every instrument and every measure will be accepted,' reads the draft. 'It will take political deftness, diplomatic skill and a willingness to compromise to achieve the climate change goals.'