As the bestselling model in Audi history, this all-new 9th generation A4 shoulders great responsibility. Compact sedans do much of the heavy lifting for luxury marquees and Audi considers the A4 representative of the best in every detail the brand has to offer.In this crossover-happy world, the Q5 is by far Audi’s most sought after vehicle but on the car side of the ledger it’s still the A4. Popular German …