LURKING behind the latest Peugeot 406's nicely cleaned-up face are a couple of new 2.0-litre, four cylinder powerplants - an all-alloy petrol engine and a torque-rich turbo diesel. Couple the new diesel with a practical and workmanlike seven-seat wagon body, along with Peugeot's renowned suspension, and you have a thoroughly impressive prestige workhorse that gives a lot, but takes little.