Car company Porsche is to mount a legal challenge to the decision by London Mayor Ken Livingstone to raise the London congestion charge from £8 to £25 for the highest-polluting vehicles.
Porsche said it believed the increase was "unfair" and was making an application for judicial review of the decision.
Andy Goss, managing director of Porsche Cars GB, said: "A massive congestion charge increase is quite simply unjust. Thousands of car owners driving a huge range of cars will be hit by a disproportionate tax which is clear will have a very limited effect on CO2 emissions."