Not claiming to be an expert, though I-ve has some 140's and 240's during the years; -73, -82, -88 and 2x-90. My personal favourite based on experience is the years -90 to the last ones in -93. These seem to have reached a level of very consistent quality of a car where mostly all bugs have been systematically eradicated throughout the years. They are also adequatly equipped with power steering and a some other options which were only for extras by the late seventies or early eighties. Not to mention rust, which seemed to have an easy game around 1980 for some reason.

When it comes to engines and general mechanical reliability, I have found that there are no major differences. I was for a long time a sceptic to modern electronics in cars, but Volvo seem to have followed the path of choosing high quality bits to do this job when it became mandatory.

In the end, as for most other cars, it's the history of care and maintenance that counts if you are looking for a reliable car. For two cars of the same standard, comfort is better for the newer ones. Simple...?