What makes you think it is the 1.8?
I realise that the 1.8T has been fitted in newer Audis, however I would have thought that if a 2.0L with better omissions and MPG is available that would have been used.
I've read a bit about the new Golf, especially since the pics were first leaked and they mentioned a number of engines including a new twin-turbo 2.0 TDI engine with 204bhp in Autocar.