John Ephgrave, of John E Cars, said the width and emissions tax would still be an 'unfair burden' on families and proposed changes made to water-down the law did not go far enough.
'There are still going to be costs incurred of up to £2,000 on a £6,000 vehicle,' he said.
'We do a lot of family car vehicles in the mid-range and the size of those engines will still incur up to £2,000 in costs.
'It's a ferocious tax on young families – they need these cars.'
Mr Ephgrave, pictured, said couples with children needed larger cars with bigger engines because of car seats, buggies and the extra weight.
Even with discounts for second-hand imported cars – of up to 65% on cars five years old or older – the cost incurred through the tax would still be high, he said.
