Porsche Cars UK has taken the unusual step of taking legal action against London mayor Ken Livingstone’s recent proposal for a £25 ($50) daily charge on high emissions sports cars and SUVs that drive though central parts of the UK capital. The new scheme will come into effect on October 27, forcing vehicles with the highest greenhouse gas emissions to pay the fee every time they enter London’s Congestion Zone.

According to a statement made by the company today, the tax will have a “very limited effect on CO2 emissions” and will “damage London based-businesses of all sizes.” Porsche goes on to claim that “successful people from across the world will start to think twice about basing themselves here if they think they are going to be used as cash cows for City Hall. The proposed increase will be bad for London as a whole and will send out the signal that it is not serious about establishing itself as the best place in the world to do business.”

Part of the problem is that the increased tax of £25 applies not just to residents outside the congestion charge zone (who would have had to pay £8 previously), but also to residents inside the zone, who pay around 80p per day - an increase of around 3025%.

The London mayoral election is coming up, so Porsche also views this tax as a populist move motivated by political gains rather than a serious attempt to reduce carbon emissions.

Porsche is requesting a judicial review of the emissions charge, which allows an individual or company to challenge a decision made by a government authority. If successful, Livingstone will be forced to change his emissions scheme to something deemed more suitable by the courts.

Porsche is currently working on hybrid versions of its Cayenne SUV and Panamera sedan, but these won’t hit the market until at least 2009. It is also working to reduce emissions throughout the 911 range. The 911 GT2, for example, is not only faster than the previous model but also uses less fuel.