The 2013 A3 is the existing "8P" model that has been in production for years. The new, MQB based A3 sedan that you referenced above has not been announced yet and likely will not arrive in showrooms until about this time next year.
So I left a deposit for a 2013 A3 a few weeks ago, great I think, I can't wait to see this new 2013 model I see all over the web. When I get to the dealer I see a black A3 from 2006 that hasn’t been updated in 8 years. WTF Audi?
I was expecting this in a 4 door:
Instead they showed me this: