My 2000 S80 T6 has been relatively trouble free. They downloaded a couple of software fixes and corrected the AM radio ground and a few other things. The issue isn't so much whether somehting broke under warranty, but whether it was taken care of under warranty.

I wouldn't focus so much on systemic issues as much as I would on what care the car has had. Unsupported blanket statements like "It uses a GM Transmission and all GM transmissions are bad" are of no use in determining which cars have a long remaining life.

There is no reason a car with 50,000 miles with has had 3k oil changes and all other fluids changed regularly and all it's maintenance performed should not run for another 200,000 miles. The problem you face is finding such a car. Most used Volvo's on dealer lots are lease turnbacks and repos. The dealers get them from auto auctions. Because their prior owners had little incentive to spend money on maintenance count on not much having been done. Partly offsetting this is that you will get (and pay for) an extended warranty for certain cars.

Ask for the maintenance records and run a carfax report on anything that looks to be of interest. And be prepared to walk away from a lot of cars. Been there done that...recently.