Uncle DaveO mentioned major repairs coming up. This means the car will have little street value unless you trick some sucker- which many of us are too honest to do.
A dealer, with his stall of mechanics, can handle the repairs cheaply (no mark-up, remember how a business handles costs and taxes, etc.) and get the vehicle to his sales lot. For a car needing repair but cosmetically good, a dealer can give a decent allowance.

His choice is, of course dependant on his (wife's) preferences. The Park Avenue is comfortable, roomy, well-built, excellent on the highway, built much like the full-size Cadillac, and has lower maintenance costs than foregn vehicles like Volvo.
A somewhat equivalent Volvo to the Buick Park Lane is costly (S80 about $60,000 new, base price here). Not a common car, so used ones are hard to find.