The organisation "London Councils" - which represents the boroughs - says charges are determined by the demand for parking spaces.
But critics claim they just add to the burden on already hard-pressed Londoners.
Our Political Correspondent Simon Harris reports:
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Khan, the Labour MP for Tooting, claims his plan to hold fares at 2016 prices until 2020 is fully costed.
Lee Drake smashed into a moped in Poplar in June 2014, after going through a red traffic light with blue lights on but no sirens.
More than a decade after their daughter's death the Dowler family were given these harrowing details of their daughter's last hours.