Formula 1 returns - the new cars of 2013 in pictures

Lewis Hamilton helps to launch the new Mercedes W04 at Jerez on Monday. Testing for the new F1 season began today at the Spanish circuit with most, but not all, of the teams present to try out their 2013 models. Hamilton, who signed a £60m three-year contract with Mercedes, says he feels "happy" with his new team, but few people expect the car to challenge for the title.