It's the mid- to late 1980s. GM quality is going up, and its sales are going down. This version of GM's venerable nameplate, along with its clone, the Buick Century, hit the intersection of these two trends: GM made a lot of them, and they lasted. Most of the bugs had been worked out on these models' forebears, the much-ballyhooed (and much-troubled) GM X-bodies.

That their first owners were seniors who drove them gently and serviced them conscientiously probably helped matters. Note that the Chevy Celebrity and Pontiac 6000, basically the same car, don't enjoy the same endurance.