Get three of the CRX mod it until you have 199 hp. Let Amber, Vito, and Chief race the free sprints until they get full skills. Then , use them in a 2-2-2 or a 3-3 circuit race.

Go into the workshop. Select a car and make it the top of a class (199 bhp, 299 bhp etc.). Then, go to the calendar and choose a sprint in the class that the car is in. Enter the race and choose one of your crew to race. When in the race, set mentality to high and they should win.