Confirm the drivetrain first: 2008-2012 coupes are the 4.2 V8 (manual or auto), while 2013+ cars and all convertibles are the 3.0 supercharged V6 — they are different ownership propositions. On V8 cars, optioning (Sports Differential arrived for 2010, Alcantara, B&O) affects desirability, and the must-see records are carbon cleaning, the cat recall, clutch, and timing chain.
Buying: be clear which engine, and demand the records
Audi S5 (B8) · buying-advice