Transport for London (TfL) has revealed where it is considering extending the congestion charge zone.
The plans show the road toll scheme could nearly double in size, taking in parts of Westminster and Kensington and Chelsea.
It could be extended along the Chelsea Embankment - heading north along Earls Court Road and Holland Road.
But the expansion of the £5-a-day charge will only go-ahead if Ken Livingstone is re-elected as mayor for another four years.
On Friday police stopped drivers on Cromwell Road to answer TfL questionnaires, as part of a feasibility study, about how the expansion would effect their behaviour.
Michelle Dix, from TfL, told BBC London: "We would use this data to understand if we extended it what the impacts of such a zone would be on traffic levels.
"Our modelling data shows we would get benefits if we extended it to such an area."
But local businesses are worried about the possible extension.
David Lidgate, whose family butchers has been in Holland Park for 150 years, said that if the zone is extended their business will collapse.
"This is a London village - we've got to have some life and that comes by car.
"And people that come by car spend more and they are the difference between profit and loss for small shops like this."
TfL said local businesses and residents will be asked their opinion on the possible extension of the congestion charge zone once a formal consultation process begins.
"The existing zone may have cut traffic but it hasn't raised as much cash as TfL hoped"