London Mayor Ken Livingstone tripled the fee drivers of the most-polluting vehicles will have to pay to enter the city center beginning in October, from about $16 to $49. The so-called congestion charge was introduced in 2003 in an effort to decrease traffic and greenhouse-gas emissions, encouraging Londoners and visitors to use public transportation instead of cars. Today’s changes to the congestion-fee program include exempting drivers of the most-efficient vehicles, including the Toyota Prius, from the charge. Another change would erase the exemption that had been in place for residents who live within the congestion zone, subjecting drivers of the most-inefficient SUVs and luxury cars to the $49 a day charge for driving in downtown London even if they live there. “I believe that this groundbreaking initiative will have an impact throughout the world with other cities following suit as they step up their efforts to halt the slide toward catastrophic climate change,” Livingstone said.