nberry:

The issue with the R8 is it looks a lot like the Audi TT. The R8 just doesn't come off looking like a high performance sport car.yes

Proportions are vastly different between the two.  The primary issue is cost.  Few want to spend over $180,000 for an Audi.   The price increase with the current model over the predecessor is the cause combined with it now longer being the new thing on the block, the McLaren 570 has assumed that role.