Today team-mates Lewis Hamilton and Heikki Kovalainen are racing black cabs for a new viral ad to launch the Taxi Grand Prix which starts on Friday 12th of June. As the Silverstone Grand Prix approaches the FI stars give their thoughts on Jenson Button, the upcoming race and how they are preparing for it.The ad for the Taxi Grand Prix features Lewis and Heikki playing cabbies competing for a fare once the cab controller (played by Extras and Eastenders actor Shaun Williamson) announces a call to collect a customer. They both race to their black cabs and dash across town to get to the fare first. The Taxi Grand Prix is a new online competition where the public can enter a team and compete in races to make the fastest time in order to win prizes. Just like in Formula1, the aim of the game is for your team of drivers to finish the race before anyone else.To enter the race all you have to do is create your team, pick your drivers and get racing. There are 10 drivers across 5 cities in the UK – Edinburgh, Manchester, Birmingham, Cardiff and London. To find out more and sign up, go to: www.vodafone.co.uk/taxigp