On Alfa number 15
AO Platinum Member
Join Date: Dec 2005
Location: United Kingdom
There is no connection between the 156 and 159, other than the factory they are built in, the people that make them and the processes in which the rust protection is applied.
People like Autolusso who see cars day in day out have already said that they have seen 159's with badly applied body protection from new.
To be honest, the 159 is still a bit too young to have serious corrosion problems surface, but I would be good money that within the next year or two threads will be popping up with regard to 159 rust.
The Brera on the other hand was built in a different factory, which has a better record of making cars which resist corrosion, so although the materials used and the design are similar I would put money on them having less issues.