 Complete the following phrase:  In 2015, the car was further developed and was categorized into the category. Bernhard, Hartley, and Webber won four out of eight races to claim the 2015 World Endurance Drivers Championship and the World Manufacturers Championship. Earl Bamber, Nico Hülkenberg and Nick Tandy won the 6 Hours of Spa-Francorchamps and 