Take a look at YouTube buyers guides. The a7 is a lovely car. You have to determine what features are essential to you like sat nav, parking sensors, Bluetooth etc as a lot of these things are extras or part of tech packs etc. Also if it's auto make sure it's had the gearbox oil services on time and same if it's got a quattro system. If quattro make sure all tyres have even wear and the brands match on each axle as either mis matched tyres or uneven wear can damage the quattro system.