THE London congestion charge will treble for large 4x4s and other fuel-hungry cars, under plans by Ken Livingstone to penalise vehicles with high levels of carbon dioxide emissions.

The Mayor of London is proposing a discount on the £8 rate for “greener” cars but an increase to £25 for “environmentally damaging” vehicles. The top rate would apply to any vehicle emitting more than 225g of CO2 a kilometre (g/km), including the Range Rover, Toyota Land Cruiser and some versions of the Renault Espace and BMW 5-series.

Cars emitting 120g/km or less, such as some models of the Citroen C2 and C3, and the Renault Clio, would pay less than £8, though the exact figure has to be decided. But the new sliding scale of charges would mean about 44 per cent of motorists paying more than £8.

Mr Livingstone said that he had asked Transport for London to draw up proposals to amend the congestion charge scheme from 2008. The discounts will be introduced first and the higher rates by 2010.

He said: “My aim is to see the cutting of carbon emissions and the protection of our environment at the heart of the [congestion charge] scheme.

“There is a growing sense of concern amongst Londoners about climate change caused by CO2 emissions, which is the biggest single problem facing humanity, and tackling this threat requires decisive action.

“I want TfL to look at lower congestion charges for cars responsible for lower-than-average CO2 emissions, broadly the retention of the current rate of £8 for most cars, and much steeper charges of perhaps £25 for the really environmentally damaging cars such as the so-called Chelsea tractors.”

The AA Motoring Trust said: “A focus on so-called gas-guzzlers smacks of jumping on a bandwagon. The hardest-hit are often drivers who are trying simply to go about their lives in the most efficient and cost- effective way.

“The war on 4x4s in London has reached new heights and is in danger of going over the top. They already pay a recently introduced top-rate road tax, and probably pay more fuel duty and VAT as they use more fuel.”

Angie Bray, the London Assembly Conservative Leader, gave warning that the move could leave families stranded and damage small business.

“Cutting pollution is a good thing but this change will hit small businesses and families.

“Reducing the charge during the period when the roads are quiet would be a much better way to cut congestion and therefore emissions.

“We all want cleaner air in London but this could be a very painful way forward.”

Sian Berry, of the Alliance Against Urban 4x4s, said that the group’s research had found that a £25 charge would deter 40 per cent of 4X4s from entering Central London.

“We are delighted that the mayor has taken on the problems caused by big, gas-guzzling cars in our city with so much enthusiasm,” she said.

“There is simply no place for these monsters in our cities and the evidence shows that financial penalties, like a £25 congestion charge, will make a real difference.”