US President Barack Obama\'\'s official car, \"The Beast,\" was facing a ?10 ($16) congestion tax Friday for driving through central London. London mayor Boris Johnson said \"The Beast\" and every other vehicle in Obama\'\'s official motorcade would be stung with the charge, the London Evening Standard reported. The British government put out the welcome mat for Obama during his state visit to the UK, with a state banquet at Buckingham Palace and an invitation to speak in front of parliament. But Johnson was less accommodating as he continued his battle between London\'\'s city hall and the US embassy, which refuses to pay the charge. He tackled Obama at the end of the Queen\'\'s banquet, and demanded the President write a check to settle his embassy staff\'\'s ?5.3 million congestion charge backlog. \"Could you please write me out a check for ?5 million?\" Johnson asked Obama, according to The (London) Daily Telegraph. Obama reportedly smiled at Johnson\'\'s cheeky request, before Louis Susman, America\'\'s ambassador to London intervened saying, \"I think this is a matter where our position is already well known,\" as the pair departed. The US Embassy refuses to pay the congestion charge, citing the 1960 Vienna Convention on Diplomatic Relations, which prohibits taxes on diplomats. The congestion charge was first introduced in 2003 as a revenue raiser for London\'\'s transport projects as well as a bid to cut traffic in the center of the city.