When Stanford's autonomous car Shelley nears speeds of 120 mph as it tears around a racetrack without a driver, observers' natural inclinations are to exchange high-fives or simply mouth, "wow." Chris Gerdes and his students, however, flip open laptops and begin dissecting the car's performance. How many g-forces did Shelley pull through turns 14 and 15? How did it navigate the twisty chicane? What did the braking forces look like through the tight turn 5?