Sadiq Khan has written to VW asking the German auto maker to "fully compensate" London residents who have been affected by the emissions scandal.

"I want to see a proper commitment from them to fully compensate the thousands of Londoners who bought VW cars in good faith, but whose diesel engines are now contributing to London's killer air," the Mayor wrote to the Wolfsburg-based company.

There has been concern expressed that while US consumers are being paid compensation, there has been no proposal made to the 1.2 million VW owners in the UK affected by the emissions scandal.

Khan wrote: "There is no excuse for the utter lack of action VW has taken in London since the ‘dieselgate' scandal came to light."

There are half a million VW vehicles registered at London addresses, about 80,000 of them dating from 2009 to 2015. These are the years when cars were fitted with software detecting when they were being tested, allowing the engines to be switched to a cleaner mode.

Khan also asked for information about VW's commitment to re-program these so-called "defeat devices" in affected vehicles.

Lost congestion charges

The Mayor called on VW to reimburse Transport for London (TFL) 2.5 million pounds ($3.12 million / 2.94 million euros) in lost congestion-charge revenue from vehicles which were not known to be contributing to pollution levels.

He said he would use the money to "fund a new schools air quality programme that will reduce the exposure and raise the awareness of schoolchildren in London attending schools in the most polluted areas." There are an estimated 448 schools in areas exceeding legal air-quality levels in London.