Even Germany's chancellor had admitted diesel's days are numbered.

The country must eventually follow other European countries in banning new diesel cars from the roads, Angela Merkel said in an interview with Super Illu magazine, according to Reuters.

"I don't want to name an exact year," she said. But Britain and France's plans to phase out internal combustion engine cars by 2040 "were the right approach", she said.

Merkel said the car industry, blighted by the diesel scandal, must win back trust, including by offering trade-in bonuses and software updates.

Consumers, who had been "deceived", must get the environmental emissions performance they had been promised, she added.

But tax breaks favoring diesel cars would remain in place for the time being, since they emitted less carbon dioxide than petrol engines, she said, according to Reuters.

Merkel added Germany should focus in coming years on building the charging stations and associated infrastructure around the country that would be needed as electric cars became more mainstream.