The size of the congestion charge zone was doubled in February 2007
The public is to be asked whether the western extension of London's congestion charge zone should be abolished, altered or kept as it is.
A five-week consultation will begin in September with people voting on a series of options for the £100m scheme.
Mayor Boris Johnson has promised to comply with Londoners' wishes on the future of the zone, which he said some people felt had been "imposed" on them.
However any changes would take another year to implement, his spokesman said.
The public have five weeks to respond to the Mayor
The extension was implemented in February 2007 by London's previous mayor, Ken Livingstone, despite objections from many businesses and residents.
After it had been in place for three months, the West London Residents Association claimed trade among 150 retailers in the Earl's Court and Notting Hill areas had fallen by a quarter.
Mr Johnson said while campaigning to be mayor earlier this year that some of those in west London felt "indignation" that "the thing was imposed against their wishes".
But Jenny Jones, who represents the Green Party on the London Assembly, urged the public to keep the zone in place.
Across London the congestion charge had been "successful in reducing traffic, reducing pollution and encouraging people to switch to public transport and cycling", she said.
Any changes would leave people wondering why Mr Johnson was "reversing a policy to reduce traffic at a time when London is struggling to improve air quality and to reduce our impact on climate change", she added.
The consultation - described by the mayor as "an exercise in democracy" - will be in the form of a leaflet outlining the options and containing a questionnaire.
Separately an "attitudinal survey" would be conducted across London, Mr Johnson's spokesman said, which would further gauge reaction to the scheme.
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