It is presumably as small as the A4 B5 series that was first launched in 1994 and the show car looks like an RS3 Sedan instead of a bread and butter A3 hatchback (Yes, I know its called Sportback, but it IS a hatchback). Take a good look at the size of the alloy wheels, its lowered stance and the aggressive front end if you disagree with my thoughts. I have to again state, look at those rims! 20inches on an A3 sized car is definitely RS3 Sedan Concept car to me.
In fact the engine gets the RS3 Sportback 4 cylinder 2.5liter turbocharged engine but with added firepower. The A3 Sedan Concept gets 402bhp instead of 334bhp. It weighs 1540kg and will do 0-100km/h in 4.1seconds. It is Porsche Cayman eating, but I would settle for 350bhp anytime as the car looks good.
A good small sized Audi sedan, soon to be back after all these years. Well, better late than never.