WHAT is it about the French and big luxury cars? Traditionally it has been their achilles heel, get beyond a certain size and all that car-building prowess evaporates. Peugeot is a case in point. The 607 launched here late in 2001 follows on from a model barely remembered in Australia called the 605 - that's because very few were ever sold here. Unfortunately the 607 may struggle to avoid the same fate, because for all its roominess, outstanding luxury items and good price it still lacks the the prestige, refinement and technical excellence of German rivals like the BMW 5 Series and Mercedes-Benz E-class.