Red Bull have announced that Spanish teenager Jaime Alguersuari will serve as their reserve driver from next weekend's German Grand Prix. Alguersuari, who became the youngest-ever British Formula Three champion last year, replaces fellow Red Bull junior driver Brendon Hartley, who has held the post since May's Spanish race. “With the ban on in-season testing, Red Bull views the appointment of a third driver as part of its young driver training programme, allowing a driver to follow all activities of the F1 teams over a race weekend,” explained the team in a statement. “Having benefited from this experience over the first half of the year, Hartley will now concentrate on his own racing programme in the European F3 series.”