THE Mayor of London has taken the city’s congestion charge policy in a completely new direction and landed in fresh controversy.

Ken Livingstone announced this month that he has ordered Transport for London to produce new guidelines offering discounted congestion charges to drivers of cars that produce lower levels of CO2 emissions. He wants the new charges to take effect in 2008.

Most cars would continue to be charged the present rate of £8 but reduced rates would apply to cars with low CO2 emissions. So called Chelsea tractors, four-wheel drives that produce more than 226g of CO2 per kilometre, would be charged £25. But the current anomalies that exempt 4x4s with hybrid power and electrical vehicles from the charges would remain.

The problem for activists and manufacturers is that the technology has moved much faster than the Mayor, who is applying standards that are already out of date. His rules are technology specific and they favour hybrids with petrol and electrically powered fuel sources, such as Lexus four-wheel drives and diesels, over bio-ethanol cars that are more friendly to the environment.

Mixing a percentage of ethanol into the petrol fuel mixture produces a clean burn, greater torque and more power from the engine, according to engineers. The ethanol is produced from sugar beet, which absorbs CO2 in the growth process and then releases it into the air again as the fuel is burnt by the car, completing an environmentally virtuous circle.

The guidelines for the congestion charge are set by the Energy Saving Trust which, until last year, created and ran the PowerShift Register that classifies the efficiency of vehicles. Transport for London is legally bound to follow the PowerShift classification.

“We’ve been telling them that they need to change. The PowerShift Register lets in things like the Shogun. It’s a nonsense,” says a Trust source.

The Mayor’s press office says in a statement that the forthcoming review of charges “will examine all vehicle fuel types including bio-fuels”.

The rundown on bio-ethanol

Bio-ethanol can be bought for 2p a litre less than unleaded petrol. The cost of bio-ethanol should remain stable because it is not linked to the oil market.