DRIVERS of gas-guzzling vehicles are to pay much more for their car tax.

But all motorists were spared an immediate rise in petrol prices when Mr Brown deferred a 2p fuel duty increase until October.

Those with the most-polluting vehicles, including some "Chelsea tractor" 4x4s, face a doubling on their annual vehicle excise duty to around £400 a year.

But the Chancellor staggered the increase for vehicles in the highest VED band - band G.

The band G rate will rise by 30% this year to £300 with another hike to £400 in 2008.

Mr Brown said that VED for band B - which takes in "green" vehicles like the Toyota Prius and the Honda Civic Hybrid - would be reduced from £50 to £35.

But cars in band F - which is the second-highest - will pay £10 more this year and £5 for each year after that. Rates for cars in bands C and E will increase by £5 a year for the next three years.

Cheaper

There was another sting for petrol-engined car owners.

Until today VED rates were slightly cheaper for them than for diesel-powered cars.

But Mr Brown said VED would from now on be levied at the diesel rate - meaning another slight rise for many motorists.

The 2p a litre rise in petrol and diesel at the pumps next October will be followed by a 2p rise in 2008 and a 1.8p rise in 2009, Mr Brown said.

RAC Foundation executive director Edmund King said: "Motorists will breathe a sigh of relief that there will be no fuel tax rise for six months.

"There is still great uncertainty in the world oil market and prices are still high."