It neither handles nor performs like the RS4 in many respects such as:- the sheer power(obviously, its a diesel!), the directness of the steering along with it's general composure on b-roads....but in fairness to the A5, it very quiet, plenty of oomph for my day to day motorway trips......and it's a heck of a nice place to sit in terms of comfort and general cruising ability....Audi were spot on when they said this was a GT cruiser type car rather than a sports vehicle.......
Bit like comparing chalk and cheese at the end of the day, but both cars at the top of the game in their respective markets IMHO........