Audi shakes down its new F1 chassis at Barcelona this week, marking the German manufacturer's formal entry into the sport after years of acquisition and reorganization. The shakedown is the first time the Sauber-based platform will turn a wheel under Audi power—a crucial moment to validate months of bench work before pre-season testing begins in earnest. How the PU behaves under real track load will tell you everything about whether this $500M commitment actually works.