Does your friend like sporty premium sedans or just luxury sedans?
For 55K I'd have the upcoming Audi RS4 on my shopping list. It may cost a tad more, but from all reports, it's worth it! The new Infiniti M45 is within his price range and mixes luxury and sport pretty well.
If your friend is more into luxury...then the awd Acura RL, or a new BMW 5 series would probably suit him/her pretty well. Heck, a Jaguar S-type won't be great reliability-wise, but the ammenities are second-to-none!
-Chike