London Mayor Boris Johnson gave qualified support today to bold plans by Formula One chief Bernie Ecclestone for a London Grand Prix.
The proposal, to be announced tonight, includes a route which would pass some of London's most famous landmarks, including Buckingham Palace and Trafalgar Square.
Mr Johnson said he was "broadly positive" about the plan as long as air quality and noise issues were addressed.
Speaking as he launched a new cable car system across the River Thames in London today, the Mayor said: "I am always interested in projects that attract jobs and bring growth."
He said it was important to see if there was "a really good economic case" for a London Grand Prix.
Mr Johnson went on: "The question of air quality and noise impact will have to be looked at. I am broadly positive providing we can satisfy the air quality and noise issues.
According to The Times, Mr Ecclestone has wanted a race in London for years and that it would cost around £35 million to stage it.
The race would start in The Mall and cars would reach speeds of 180mph on the 3.2-mile circuit, with drivers racing past Buckingham Palace.
The Times said marketing experts predict that the race could generate at least £100 million for the London economy from spectators and tourists.
Mr Ecclestone told the paper: "With the way things are, maybe we would front it and put the money up for it. If we got the OK and everything was fine, I think we could do that... It would be fantastic, good for London, good for England - a lot better than the Olympics."
Londoners seemed fairly relaxed at the idea of ultra-fast cars whizzing through the capital.
"I think it's very exciting. I am 100% in favour of it," said Maurice Bennett, 79, from Hampstead, north west London.
But Bernard Boreham, 68, from Croydon, south London, was less happy.
He said: "I am not so sure about this. I would rather see cars going around a racing track outside London."
Robert Davis, deputy leader of Westminster City Council, said: "We are yet to receive any firm proposals from the parties involved, but we would very much like to form part of the discussion process.
"This is an event that would have obvious benefits to London in terms of finance and profile - but the council will wish to also put forward any concerns we receive from residents."
London Assembly Green Party member Darren Johnson said: "Bernie Ecclestone's proposal is a terrible idea at a time when we want to make our streets safer and more pedestrian and cycle friendly.
"Formula One should stick to the dedicated race tracks and leave our streets for ordinary Londoners to enjoy. I hope the Mayor joins me in opposing this idea, which is completely unsuitable for London."