Get ready for a proper old-fashioned scrap. Porsche is gunning for Ken Livingstone over his plans to increase the top-end congestion charge... and we can't see either camp backing down.

Porsche says it plans to ask for a judicial review of the price changes, which come into force in October and will see cars producing more than 225g/km of CO2 paying £25 per day to enter the zone, while cars emitting less than 100g/km of CO2 will drive for free.

The German manufacturer believes that the new rules are 'disproportionate' and will not lower emissions levels in central London, and plans to write to the mayor's office.

"A massive congestion charge increase is quite simply unjust," said Porsche GB's Andy Goss. "Thousands of car owners will be hit by a disproportionate tax which clearly will have a very limited effect on CO2 emissions.

But Red Ken doesn't seem likely to change his mind. "No one needs to drive these really big polluting cars in central London," said Mayoral advisor Mark Watts. "You will have to pay for the cost of pollution that you inflict on everyone."

Transport for London believes that two-thirds of the 33,000 top-rate vehicles currently using the charge zone will no longer enter the zone when the new fees are introduced.

It looks set to be a cracking fight. Get your front row seats and popcorn now.