Ministers are being urged by a leading environmental campaigner to stick by controversial plans to increase vehicle excise duty on older cars.
Labour's David Chaytor (MP for Bury North) wants to see the Government press ahead with the measures announced in March's Budget that would see tax increases for many cars registered since 2001.
Tories and Labour backbenchers have attacked the proposed change, which is reportedly set to be postponed when Chancellor Alistair Darling reveals his pre-budget report in November as part of a package to help hard-pressed families cope with the economic downturn.
The move would see all cars registered from 2001 classed into new VED bands depending on their CO2 emissions from next year.
By 2010-11, 9.4 million drivers could face higher bills - 43% of the predicted number of vehicles on the road, according to Treasury figures.
Some 8.4 million will pay around the same, while 1.4 million will see their payments fall under the changes which are due to come into effect in April and are designed to hit the heaviest polluters hardest.
Mr Chaytor, a Commons Environmental Audit Committee member, said: "The use of graduated emissions-based VED is an important measure.
"Exempting the current vehicle fleet from graduated VED, as the forces of conservatism on all sides of the House have been lobbying for, would actually be counter-productive to the Government's climate change strategy."
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