After multiple attempts, I am conceding that it is not feasible to complete the British GT Cup with one of the unmodified pre-purchase prize cars. After completing the Sarthe Circuit 24 Hours II race, my stock GT4 run topped out at 48.5% completed. My next step was to equip the Jaguar XJ220 LM Edition '01 with Road Tires to complete the British GT Cup. Thereafter, I did the same to the Subaru Impreza Super Touring Car '01 for the Boxer Spirit race. Upon completion of those two races, I had managed a 50% completion rate and earned the Jaguar XJ-R9 Race Car without spending any credits. At that time, my game stats read as follows: Days: 452 Prize Credits: 10,452,000 Trophies: 243 Prize Cars: 94 At present, I intend to attack the rest of the game by purchasing a vehicle for the Sport Truck Race. The $24,520 spent on the Toyota Tacoma X-Runner '04 will allow me to close out the Beginner and Professional Halls to open up the Extreme Hall. That one purchase should help me get my completion rate up to around 60% without any further purchases.