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.

When my son got his first job and needed a car in a hurry to commute I helped him get his first car and in the search we wound up looking at a lot of Buicks that we liked and were at a good price and in good condition, particularly circa 2005 though we wound up with a '96 Park Avenue. It was my first experience owning an American car (title in my name for the cheaper insurance) and my own experience plus what I read indicates I probably would have done well with one of the 2005s.

My take is that at that age you don't pay that much more for the upbadged car but you're likely to find it in good condition but you get to enjoy the bling (the '96 is ahead of its time with traction control) and Buicks of that vintage have one of the best engines GM ever made.