Better incentives for cleaner fuels and an overhaul of taxes are some of the things motoring groups are calling on Chancellor Gordon Brown to deliver in Wednesday's budget.
Although fridge-style energy efficiency labels were introduced last year to help motorists choose greener cars, the RAC Foundation says they don't go far enough.
It wants to see a new top vehicle excise duty band created where motorists driving more polluting cars would pay more, and cheaper bills for cars at the other end of the scale. Currently the biggest tax difference between the least and most polluting cars is just £100.
Executive director of the RAC Foundation Edmund King said: 'We think Mr Brown can send out a green signal to motorists to think more about their choice of vehicle.'
The AA Motoring Trust agrees that there could be a slight increase in the top rate of duty, but says the £10 surcharge levied on diesels should be scrapped.
However, the Society of Motor Manufacturers and Traders (SMMT) says any Vehicle Excise Duty change should be ruled out by the Chancellor. It believes consumers need time to adjust to new efficiency labels, and is concerned that any change could have an unforeseen impact on sales and manufacturing.
Instead, the SMMT wants Mr Brown to clear up the confusion over the Powershift grants, which used to provide cash for motorists to convert their cars to run on liquefied petroleum gas (LPG). However, the scheme was ended a year ago, and motorists don't know if any money may be available in the future.
SMMT chief executive Christopher Macgowan said: 'Government has to embrace the concept of incentives in driving the market for the cleanest vehicles.'
Come back to whatcar.com on Wednesday to find out what the Chancellor has in store.
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