Future classics IMO (although not all are saloons, so sorry Dingle ):

First M-Coupe "Bread van"
E46 CSL (no other M3s, as they built too many).
All the previous M5s to the current V10 version.

Evo 6 RS

R32 Skyline GTR V-spec

Focus RS (again - limited numbers)
Puma Racing (again - limited numbers)

Some cars that are already attaining classic (i.e. cost shit loads) status:
993 Turbo
993 RS
964 RS
Mint E30 M3s