More than three-quarters of car-owners estimate they will be worse off under the controversial new road tax rates, according to a poll conducted by This is Money.
In response to the question 'How will the car tax changes affect you?', 77% said their car tax will increase when the new rates are introduced in 2010.
The figure is considerably higher than official estimates, which have already rubbished ministers' claims that the vehicle excise duty overhaul - sold in the Budget as a green policy - would have little impact on motorists.
>> LOOK UP YOUR NEW CAR TAX
The Treasury yesterday admitted that almost half of the UK's car owners will be up to £245 worse off under the plans, while only 18% will see their tax fall. In May, Gordon Brown said that 'the majority of drivers will benefit from it'.
Only 7% of the 2,307 respondents to This is Money's poll said they would see a fall in their tax.
The Treasury said that from April 2010 it will cost more to keep 43% of all cars on the road - some 9,423,450 vehicles. The figures show that 1m drivers of cars registered between 2001 and 2006 will see road tax jump from £210 to either £430 or £455 depending on emissions, while others face hikes of between £10 and £155.
Meanwhile, just 4m cars out of the 22m on the road will see the price of a tax disc fall. Owners of the remaining 39% - 8,546,850 cars - will pay the same. Of This is Money readers, 16% said they will be unaffected.
The new regime starts to kick in next year but the biggest changes will hit in 2010 - weeks before the likely date of the next General Election.
However, the Treasury revelations have stoked discontent among Labour backbenchers, which threatens to turn into a full-scale rebellion. And the policy suffered another blow today when Gordon Brown's green guru pointedly failed to back it.
Lord Turner, who chairs the committee which advises the Government on climate change, stressed that environmental taxes should be 'intelligently designed' and signalled well in advance so people could change their lifestyle to avoid them.
In an interview with the Evening Standard, former CBI chief Lord Turner of Ecchinswell, backed green taxes to address global warming and praised Labour's 'showroom' tax but significantly did not offer support for VED rises for older cars.
While repeatedly stressing that he did not want to comment on the current row on environmental levies, he said: 'The ones least controversial are always the ones that people feel they can avoid because they come at a point of decision.
'For instance, one of the things that the Chancellor did in this year's Budget was to increase this first year VED distinction so when you buy a car it goes up to £900 for a big gas guzzler and a very low figure for a small car.
'That one is reasonable and uncontroversial. As much as possible, we should set these things out in advance. Looking forward over the long term, we certainly do see a role for intelligently designed taxes such as firstyear VED to encourage people to make the different decisions that they can make.'
MPs are calling for Mr Brown to perform yet another U-turn and make the road tax increases apply to new cars, so people can choose a greener model and pay lower VED, rather than hitting cars up to seven years old that people already own.
