Manufacturers have been criticised for confusing X-plate customers with “a mixed bag of reductions, cashbacks and spec changes”.

The Consumers' Association welcomed new Government rules which it said should lead to price cuts within a few months. Phil Evans, Consumers' Association principal policy advisor, called on carmakers to “listen to consumers and dealers, respect the rules and bring prices down”.

The launch of X-reg should have been used by carmakers as a clean break from their past abuses, he said.

“It is a shame the big manufacturers have chosen to waste the opportunity,” said Mr Evans. “They appear not to have noticed that record numbers of UK consumers are buying in (mainland) Europe or delaying their purchase until clarity returns to the market.”

Some carmakers had cut list prices, as consumers had wanted, but some were “bragging” about price cuts which were really marketing gimmicks.

“Others have hidden price cuts under the guise of 'special editions' and some manufacturers still refuse list prices but instead offer cash incentives,” said Mr Evans.

The Consumers' Association has advised retail buyers to choose a car, research the price at their local dealer and compare it with European import options.