The RAC, which carried out the research, said the expansion of the zone - due to start from 29 August this year - will have a “massive financial impact on motorists and businesses”.
The news comes a day after Transport for London (TfL) claimed that nine out of 10 cars seen driving in outer London on an average day already meet the ULEZ standards, so would not be liable for the charge.
TfL also claimed that many drivers are switching from older, more polluting vehicles ahead of the expansion.
The controlled zone is currently limited to the area within London’s North and South Circular roads, but Mayor Sadiq Khan has moved to expand it to cover the whole of the capital in an effort to improve air quality for all residents.
Most diesel cars registered before September 2015 and petrol cars registered prior to January 2006 are liable for the ULEZ charge.
Driver and Vehicle Licensing Agency (DVLA) figures obtained by the RAC show that 691,559 licensed cars...