AUDI has completed the MY09 A6 Series II facelift with the introduction of the entry-level 2.0 TDI and 2.7 TDI V6 sedans. Brought in to bother the popular BMW 520d as well as the introduction of the all-new Mercedes-Benz E-class, this diesel duo have price, economy and low emissions benefits, as well as the usual A6 attributes such as design, space and comfort. But do the new diesels help keep the ageing Audi up to date against increasingly newer competition?