German ministers have announced that free public transportation will be trialled in five cities by "the end of this year at the latest" in an effort to reduce road traffic, meet EU air pollution targets and avoid hefty fines.
Three ministers, including the environment minister Barbara Hendricks, wrote a letter to EU environment commissioner Karmenu Vella revealing the plan. "We are considering public transport free of charge in order to reduce the number of private cars," the letter reads.
"Effectively fighting air pollution without any further unnecessary delays is of the highest priority for Germany."
Germany is one of eight EU member states that failed to meet a 30 January deadline to meet EU limits on nitrogen dioxide and fine particles. The commissioner gave the countries additional time to present new measures for reducing emissions, or they will face legal action.
France, Spain and Italy also failed to meet the deadline. Any such legal action would be taken at the European court of justice.
Pollution in 130 European cities is considered "life-threatening" according to the EU commission, and causes roughly 400,000 deaths and €20 billion (£17.8 billion) in health spending each year.
The unexpected trial will take place in the cities including Bonn, Essen and Mannheim. Other proposals include ticketless travel, support for carpooling schemes, further restrictions of bus and taxi emissions and new low-emissions zones.
Public transport is extremely popular in Germany, where approximately 10.3 billion journeys were completed last year, largely because it is more convenient than in other EU countries. For example, while a single ticket for the London Underground costs a minimum of £4.90 (€5.50), the equivalent in Berlin costs €2.90.
However, the cities where the scheme will be trialled out, warned more details were needed before implementing the proposal.
"I don't know any manufacturer who would be able to deliver the number of electric buses we would need" to meet increased demand if transport was free, Bonn mayor Ashok Sridharan told news agency DPA.
Helmut Dedy, the Association of German Cities chief, said the cities expected "a clear statement about how [free transport] will be financed".
The proposals are particularly significant as it comes only two years after the Volkswagen scandal over emissions tests cheating which sparked a global backlash and multiple lawsuits.
At the beginning of last year, VW admitted it installed software into diesel engines on nearly 600,000 vehicles in the US that allowed the engines to turn on pollution controls during government tests and switch them off in real-world driving.
The German giant subsequently agreed to pay the US Justice Department $4.3bn (£3.1bn), the largest fine the American government had ever handed a carmaker. Six of its executives were also indicted for their role in the diesel emissions scandal that impacted around 11 million cars worldwide.
Additionally, any proposals to limit the use of cars are likely to have a major impact in Germany, the largest car manufacturer in Europe and the fourth-largest in the world, according to the International Organization of Motor Vehicle Manufacturers.
However, the car lobby has had to confront an increasing powerful environmentalist movement, which last year launched court cases aimed at banning diesels from parts of some city centres in Germany.