Plans to triple London's congestion charge for the highest polluting vehicles are expected to be announced by London Mayor Ken Livingstone.
The highest polluting vehicles will pay a daily charge of £25 to enter the congestion charge zone, London Mayor Ken Livingstone has announced.
Transport for London (TfL) has been consulting on proposals to increase the charge for gas-guzzling vehicles from £8 to £25.
Mr Livingstone also revealed that cars with the lowest carbon dioxide (CO2) emissions will receive a 100% discount from the daily charge.
Cars emitting the lowest amounts of greenhouse gas emissions could be exempt from the charge.
Most drivers will still pay the £8 road toll for entering the zone which covers parts of central and west London.
Mr Livingstone will deliver the plans at London's City Hall on Tuesday.
The new charges come into force on 27 October.
The proposals are being seen as a crackdown on the owners of 4x4 off-road vehicles.
'Chelsea tractor'
Small car discount
Mr Livingstone, making the announcement from City Hall on Tuesday said: "Nobody needs to damage the environment by driving a gas-guzzling Chelsea tractor in central London.
If the £25 charge is introduced, it will take effect from October and be reviewed in 2010.
"The CO2 emissions from the most high-powered 4x4s and sports cars can be up to four times as great as the least polluting cars."
The charge would be imposed for cars with CO2 emissions of 226 grams per kilometre (g/k) or above. Vehicles with 120g/k or less would get a 100% discount.
The mayor added that he hoped his initiative would have an impact throughout the world, with other cities following suit.
It is estimated that the majority of cars would continue to be liable for the standard £8 daily charge under the new proposals.
He said Transport for London (TfL) would closely monitor the scheme, adding that the new scheme was flexible and that the charges and exemptions could be varied in the future.
Introduced in February 2003, the congestion charge was initially £5 a day and confined to an area of central London.
Climate action
Since then, the daily rate has gone up to £8 and an extension to the west added.
Mr Livingstone's climate change action plan aims to reduce the capital's CO2 emissions to 60% below 1990 levels by the year 2025.
In London, transport (excluding aviation) accounts for 22% of all CO2 emissions, with cars and motorcycles accounting for nearly half of this.
The city won this year's Sustainable Transport Award from the US-based Institute for Transportation and Development Policy for its "leading role" in green transport initiatives and the congestion charge.
