One small flaw to Mr Tallroo's theory, what about the 30x range, which moved from 305 to 309 then 306 then 307? Well actually the theory would hold if it where not for that flaw, and I would blame Peugeot for the muddle up, but i'm sorry one exception is enough to disprove a theory.
Peugeot is a family run business, which has currently merged with Citroen to form the PSA group (do not ask me what P, S and A stand for), even though they produce different cars. In fact the cars are not so different after all, each car has a corresponding car (or will have one soon) in the other make. Interior quality of the smaller cars has recently fallen behind standards, with the plastics of the 206 looking too similar to cars produced 10 years ago for comfort. The larger cars are much more refined, with the 307 competing seriously in its sector, and the 607 not doing too badly either. Despite lacking character, the 607 is a very good all rounder, looking fabulous and being very well kitted, but it does not match it's German rivals (namely BMW, VW, Audi and Mercedes)