Buick is gonna be less ragged out than an Impala or Olds of same age (you see the same with the Grand Marquis vs the Crown Vic). An 05ish one will come with a 3400 or 3800v6 which was pretty solid and cheap to own by then. The rest of the car is nothing special, just keep oil and coolant in it and drive it.

Basically he's picking a very well sorted platform of a vehicle and then choosing the brand that most correlates with buyers who'll keep it in good order.