Feb. 26 (Bloomberg) -- Porsche SE, the maker of the 911 sports car, should produce fuel-efficient models rather than interfere in London's plan to boost charges on drivers of the most-polluting vehicles, the city's mayor said.

The Stuttgart, Germany-based carmaker said last week it may challenge Livingstone's plan to triple the daily congestion charge to 25 pounds ($49) for vehicles that emit the most carbon dioxide.

``They should be redoubling efforts to produce less- polluting cars,'' said Mayor Ken Livingstone, at a news conference today. ``I can imagine how annoyed Berliners would be if a British company tried to intervene in a mayoral election.''

Livingstone, who has made environmental issues a top priority, is seeking a third term in a vote on May 1, and his two main challengers don't support the increased congestion charge. Livingstone said a poll in December showed about 70 percent of Londoners backed the higher fee.

The carmaker said on Feb. 19 that it's considering filing an application for judicial review to the Royal Courts of Justice to challenge Livingstone's planned change to the charge, which he unveiled on Feb. 12.

The company disputed the mayor's claims today. Porsche ``is not interested in the election at all -- we're not a political company,'' said Andrew Davis, a spokesman. ``We are simply fighting on the issue of modifying the congestion charge.''

The new rule, to take effect in October, would require owners of vehicles that emit more than 225 grams (0.5 pound) of carbon dioxide a kilometer (0.6 mile) -- the so-called ``G band,'' rating used for calculating U.K. vehicle tax -- to pay the increased fee. The charge will be waived for owners of the least-polluting vehicles, Livingstone said on Feb. 12.

Boxster, Cayenne

The German carmaker's least polluting vehicle, the 245- horsepower Boxster, emits 222 grams of carbon dioxide per kilometer, while its most powerful, the Cayenne sport utility vehicle with 500 horsepower or the same as a heavy commercial truck, has a rating of 358 grams per kilometer.

The company will introduce a gasoline-electric-powered engine in an all-new sedan and in the Cayenne starting next year, Davis said. Porsche sells about 2,500 cars a year in London, and invests about 125 million euros ($186 million) a year in research into making cars more environmentally friendly, Davis said.

Porsche's polling shows that 74 percent of Londoners believe the 25-pound charge is unfair, the company said.

The new charge will raise 30 million to 50 million pounds a year, Peter Hendy, London transport commissioner, said Feb. 12.

About 150,000 cars enter the congestion zone each day, including about 30,000 Band G and 3,000 lower-polluting Band A or Band B vehicles, the city said. Some 70,000 fewer cars enter central London daily since the charge was introduced.

The zone takes in the West End entertainment and shopping areas, the City financial district and neighborhoods such as Notting Hill, Kensington & Chelsea and Knightsbridge.

To contact the reporter on this story: Brian Lysaght in London at blysaght@bloomberg.net.

Last Updated: February 26, 2008 11:28 EST