 Complete the following phrase:  A total of 29 cars were officially entered for the 6 Hours of Silverstone with most of the entries in the Le Mans Prototype 1 LMP1 and Le Mans Prototype 2 LMP2 classes. The 2014 race winners, Toyota, returned to defend their title. Three manufacturers, Porsche, Toyota and Audi Sport Team Joest, were represented in LMP1 by two cars each. Team ByKolles were the sole LMP1 privateer team partaking in the race. Nissan were scheduled to debut two GT-R LM Nismos at the circuit but decided to forego the first two rounds after issues with the car during testing. The team decided to focus on making its debut at the 