Late 70s to mid 80s, most any of them. Regal, Century, Electra, Park Avenue. 77-85 or so. The Buicks, of course, are quite a bit pudgier--the smaller ones have no more interior room than a 740, but weigh 1000 lbs. more and are two feet longer and 6-8 inches wider as well. They also have a considerably plusher interior that still manages to look cheap and tacky. If you think the Volvos are overdone with all the color-coordinated trim parts (in four different shades of mismatched plastic) remember that it was GM that first came up with the concept of color-coordinated interiors.

The 740/Buick similarity is further enhanced in the US market by the four rectangular sealed beam headlights on the early cars (up to and including 89) They were identical to those used on Buicks, and just about everything else. Until the 1986 model year, ALL cars sold in the United States were required to have sealed beam headlights, which were available in four different types: 7" round, one per side. Introduced 1939; 5 3/4" round, two per side. Introduced 1957; They can be paired horizontally, vertically or even diagonally (61 Chrysler) Outer or upper is high/low beam, inner/lower is high beam only; Rectangular, two per side. Introduced 1976; Rectangular, one per side, introduced 1979. Sealed beams were widely disliked at the time, and were indeed inferior to the European H4 headlights, at least when the two sizes of round lights were being compared. In 1986, the law was changed, and headlights could be of any shape. This quickly led to a proliferation of styles, many of which were molded in cheap plastic that turns yellow after a few years. (sealed beams usually don't deteriorate, they just go until until they burn out--reflector doesn't corrode, lens doesn't turn yellow) Plus, suddenly, a replacement headlight costs $200 instead of $4.99, and they call it progress.

Unfortunately, I have forgotten the name of the stylist responsible for the first generation of squared-off Buicks, who then went to Volvo, where he did much of the 760. He finished his career at Mazda, where he had major input on the design of the Miata, and then he did the 3rd generation RX7, which, in my opinion, is one of the best looking cars ever to have come from Japan. (and about as un-Buicklike as you can get) Interestingly, he was a Japanese-American. I think his first name was Tommy.