Sadiq Khan has asked Transport for London to start feasibility studies for the plan to raise £500m a year.
The boundary charge would be levied on vehicles registered outside the capital crossing into the whole of London – an area almost 80 times larger than the central congestion zone.
An independent review into TfL’s finances, which have been badly hit by the loss of tube fares after the pandemic, suggested that road charging would be the best source of new revenue.
The review said cuts to bus services in outer boroughs, scrapping the night tube, and ending the subsidy for the “Boris bike” cycle hire scheme would provide potential savings but could inflict further congestion and economic damage.
The independent panel was commissioned by Khan during fraught negotiations with the government for emergency funding, after passengers were told to avoid public transport to help stop the spread of Covid-19.
Khan urged ministers to “play fair” by London to assure the future funding of the capital’s transport network, and to allow the capital to keep the £500m a year paid in vehicle excise duty by London-based drivers. Khan said the money is spent outside London while TfL uses fare income to fund maintenance of major roads in the capital.
The boundary charge could also reduce congestion and emissions and encourage greater use of sustainable transport. On an average weekday about 1.3m vehicles travel into London.
Development, consultation and implementation of the scheme would be expected to take at least two years.
Khan said: “Ministers have failed to play fair by Londoners when it comes to financing our world-renowned transport system. It is high time they did so. It is not fair on London that our drivers should subsidise the rest of the country’s roads and get nothing in return.
“We can’t go on expecting public transport fare-payers to subsidise the costs of road maintenance.”
Green groups welcomed the proposal and urged Khan to go further with smarter road charging schemes.
Business group London First said a range of measures were needed but the boundary charge “could certainly be part of such a package”, while urging central government to give London more powers to raise revenue.
Logistics UK said the charge would be “a significant blow” to the road haulage sector and only paper over the cracks of TfL’s problems.