Vehicles causing the most pollution in central London are to face huge increases in the congestion charge, mayor Ken Livingstone has announced.
London residents with band G cars will lose their 90% discount
The daily charge for vehicles in carbon emissions band G, which includes some 4x4s, is to rise to £25 from 2009.
In 2008, the charge will be removed for cars in Bands A and B which produce the lowest emissions, Mr Livingstone said.
A 90% residents' discount for people living in the charging zone will be withdrawn for vehicles in band G.
But the AA said the policy would not only hit so-called "gas guzzlers" but family cars and people carriers.
HIGH EMISSION CHARGES
Cars in band G include the Range Rover 4.4 V8 petrol, Renault Espace 2 litre petrol, Porsche 911 Carrera Coupe 3.6 and BMW X5 4.8 litre
They emit more than 225g of CO2 per kilometre
Will be charged £25 for entering the congestion charge zone
The congestion charge scheme has been running since February 2003. The tax rose from £5 to £8 a day in July.
Most cars, in band C, D and E will be unaffected and will continue to pay the £8 rate.
Mr Livingstone said: "Most vehicles that will be charged £25, in vehicle excise duty band G, are high-priced models.
"Those who buy them can afford to choose from pretty much the whole of the mainstream car market but have chosen to buy one of the most polluting vehicles.
"By making these changes to the congestion charging scheme we are encouraging people to take into account the impact of their choice of new car on the environment and the planet."
LOW EMISSION CHARGES
Car bands A and B include the Honda Insight petrol-electric hybrid, Smart diesel and Toyota Prius 1.5 litre petrol-electric hybrid
They emit less than 120g CO2 per kilometre
Will be free to enter the congestion charge zone
There are no cars on sale in Britain in band A
Paul Watters, from the AA Motoring Trust, said the new charges would hit a lot of families when the zone was extended westwards in February.
"This is another attack on people carriers and larger ordinary vehicles," he said.
"Band G sweeps in a lot of family cars such as the two litre Ford Mondeo automatic and the two-litre Citroen C8 automatic, which will mean a lot of households being hit when the charge zone is expanded."
He added the cost of administering an emissions-based congestion charge with current technology would make it prohibitively expensive.
London Assembly (LA) Liberal Democrat spokesman Geoff Pope welcomed the move, saying: "Two years ago, we championed using congestion charge bands to hit the hated 'Chelsea tractors'.
"They are damaging and unnecessary vehicles in a densely urbanised, 21st Century city."
The LA's Green Party said it was "fantastic news" which would mean "the end for the Chelsea tractor".
The National Alliance Against Tolls said: "Band G cars will pay more from 2009, but that band only relates to cars registered after 23 March 2006, so it could have a perverse effect by encouraging the use of older vehicles."
South-west London's Richmond Council, which three weeks ago was the first local authority in the country to announce plans for emission-based residents' parking charges, described the announcement as "tremendous news".
Although the £25 band G charge is to start in 2009, the mayor has asked Transport for London (TfL) to examine the possibilities of it being introduced before then.