FLEET experts have attacked Government plans for a two-tier graduated vehicle excise duty system, with new cars judged on emission levels and those already on the road charged according to engine size. The Government is understood to be considering the system as it bids to introduce graduated VED starting at £100 for the 'cleanest and smallest cars' next year, but fleet campaigners say it would be unfair and unworkable.

Both the British Vehicle Rental and Leasing Association and the Association of Car Fleet Operators have slammed the idea which follows Chancellor of the Exchequer Gordon Brown's Budget announcement. According to the Government's own figures, the cleanest cars are not always powered by the smallest engines - the 1.9 TDi SEAT Ibiza, for instance, is Britain's most fuel efficient vehicle and one of the cleanest.

BVRLA director general Norman Donkin said a two-tier system - differentiating between new and existing vehicles - would not be welcomed. 'If you can measure emissions on new cars why can you not measure emissions for existing cars? Engine size could be totally irrelevant,' he said. And ACFO director Stewart Whyte said it would take considerable time and money to adapt the Driver and Vehicle Licensing Agency's systems to cope with such a scheme.

SMMT head of policy Paul Everitt said: 'It's unlikely whether establishing a two-tier system would actually have any significant environmental impact. What we should be doing is trying to reward people who have adopted good environmental practice.' A consultation paper on graduated vehicle excise duty is due to be published before the end of the year.