What to buy question budget 20 k

[taxboy]

I know it's another of these questions but would appreciate fellow PH's input. The budget is 20k and I'm not looking at buying brand new. Criteria must be auto comfortable over distance solid and not crippling in running costs with a bit of style. I'm hoping you can confirm my thinking or throw other suggestions into the mix. Current mileage 15k a year with a daily commute of 40 miles on A roads. My previous car was an E39 BMW 520. Current contenders BMW 520d - I would probably be happy with a new shape 3 series but budget won't allow a decent spec. Audi A5 sport back nice interior but concerns about the auto box. Also consider an A6 again the auto box issue though. Merc 250 diesel a bit dull in previous model but may be doing it a disservice - also believe autobox oil needs changing every 50k so running costs may be an issue. Finally Jag XF like the looks and interior but budget only allows a 3.0 diesel & scared about running costs. Sorry for rambling on but tried to provide as much info as possible. Over to you chaps