Maybe is the obsessive silver paint of the German cars or maybe is the fact that these two cars have similar dimensions and the design is relatively usual for both cars. Or maybe the designers of the Audi A5 and of the BMW 3-Series Coupe were mates there in Germany, but for some people the similarities between the cars are evident.

Yes, the tail-lights are placed in the same part of the back-end, and the general form is quite similar. From my point of view the back-end is similar if we have to discuss about resemblances, with that edge that split the rear bar from the upper side. And also the exhaust tips which are mounted similar. The integrate spoiler is also an element to be studied for this idea.

From the side-view the only similarity is the edge that flow from the back to the front, and make the wheel-arches. .If you want a conclusion the design of the both cars has limited similarities for me at least, you have to compare yourself and you may give us some opinions. The recipe is the same for both coupes, and also the general form, but on each car the maker trace their own definitive symbols in terms of design.