There are loads of ways I could spend £10k, but one I've always fancied would be a 2.0 Zetec converted Mk1 Fiesta. Originally, I fancied one in Gulf colours, but I'm a bit old for that now, so it would probably be Ghia based in a nice sedate metallic hue.. Opening quarter lights, velour seats, all standard looking, but with the suspension suitably stiffened and an unassuming set of slightly larger wheels to accommodate bigger brakes.
I'm sure I'll think of something else soon!!