Under Friday’s very overcast skies the teams focused mainly on learning about set-up, actuation of their drag reduction rear wings, KERS and how the hard and soft compound Pirelli tyres behaved on the Shanghai International Circuit. The track remained slippery throughout the day, and generally tyre degradation levels seem to be between those in Melbourne and Malaysia, with Pirelli expecting most to pit twice on race day. We take a team-by-team look at progress