Lance Bradley, UK sales and marketing director, told Motor Trader there was “not a great deal of logic” in London mayor Ken Livingstone's plan to increase the daily charge to £25 for cars emitting 225g/km Co2 or more.

“It is not a well coordinated plan to heavily penalise one group of vehicles over those emitting one gram less,” said Bradley.

Bradley suggested a more sensible approach might have been to raise the charge by 10 pence for every extra gram of Co2 emitted.

However, he admitted the new charge would force carmakers to reconsider the emissions issue in order to sell cards in London.

Bradley also said that with low emission petrol and diesel cars set to be exempt from the charge manufacturers might be discouraged from developing electric vehicles.

Meanwhile, the battle between Livingstone and Porsche, which has threatened legal action over the initiative, has continued.

In a new ICM poll conducted on behalf of the luxury carmaker a majority of Londoners said the new charge was too high, three out of four opposed the plan.

In response to the survey, a spokeswoman for the mayor said: “Porsche's flawed survey has no validity.

“Participants in the survey were given totally misleading information about which vehicles would be affected and why a higher charge was being proposed.

“This survey is part of a campaign by a blatantly vested interest, a luxury car manufacturer with high Co2 emitting cars.”