So your basically after a family saloon/hatchback with a bit of poke but economical to boot. Ok then, the Audi range would see you looking at A4/A6 quattro to avoid the fwd, 3.0 TDi engine would be nice of course, autrotrader has plenty of 54/05 plate A6 3.0 TDi quattro's about £12k, might have 70k odd on the clock but thats nothing really, they're nicely run it! They're 221bhp & 450nm torque so very quick, but a band F tax, not so good! The older shape 330d's would be in your price range too, better looking than the newer saloon imo, only 184bhp & 390nm torque so down on power to the Audi engine, but a band E tax. The Ford Modeo ST TCDi might be fwd but totally dripping with kit, a great engine which being a 2.2 TDi (152 bhp & 360nm torque) its only a band D tax to good there too! '05 platers are only £7-8k so dirt cheap to buy & run! Good looking too imo! For rwd there's the Merc C-class 320d with a 3.0 engine with 224bhp & grou F tax, at about £15k its bursting the budget a little though! Or you've got the Passat, basically a slightly cheaper A6, but the biggest engine is the 2.0TDi 170bhp engine in it, but it still hits a group E tax band.
And thats me out of sensible ideas! If my heart ruled i'd be looking at the A6 3.0TDi but if my wallet ruled the Ford St TDCi would win!