Some very good Jaguar XFR's out there at prices below £30K. Even 2010MY 5,0L Supercharged with 510 PS. Zero to 60 in 4,7 secs. Come with all the seats typical of a medium sized saloon - Mondeo, Passat etc.
Maserati Quattroporte... fast, Italian, oodles of space at the back, guess servicing and parts might be on the dear side. Proper fast and big, ticks my boxes anyhoo.