What alternatives should I consider to a used Volvo S80 saloon?
The Audi A6 is perhaps a tad classier than the Volvo, because its interior is of higher quality and it has a posher badge. It might not seem quite as stylish inside, but the A6's infotainment is vastly superior and much easier to use, although you won't get the same level of safety tech unless you find one with lots of options fitted.
If you want an executive car that can cover all basis, there's little to challenge the BMW 5 Series. Extremely good refinement, decent efficiency, a high-quality interior, excellent infotainment and tidy handling make this big BMW a great choice. Again, you won't get the same level of safety equipment as you get in the S80, but that's the only downside.