Purchased this car used from a dealer, one owner, with only 43,000 miles on it. The interior looks brand new and the exterior is nearly flawless. Amazing amount of car for the money and a much better performer than the Lincoln Town Car or Toyota Avalon. Amazingly comfortable front power seats, great fuel economy (30 hwy), lots of room everywhere and a pleasure to drive. The Park Avenue soaks up bumps very well and provides a comfortable ride. Maintenance costs very low and also very inexpensive to insure. I think I'm a new Buick fan!
Seat comfort, fuel economy, control layout, overall styling, extra features: compass, auto-dimming mirrors, very good factory radio ("Concert Sound III").
The Lucerne has succeeded the Park Avenue, so no improvements coming. However when it comes time for maintenance I might replace the stock shocks with something slightly firmer for better handling on winding roads.