I'm looking to purchase an A3 diesel, either the 1.6 or the 2.0 litre TDI. I've got a budget of around 7000 8500 so looking at 2010ish with about 70000-80000 miles. I do quite a lot of motorway miles for work which is why I'm looking at an efficient diesel.

What are the major differences between the 1.6 and 2.0 litres and which one shpuld I go for?