We (my wife, 2 daughters, and me) had 5 740s (3 wagons, 2 sedan) and 3 850s (2 wagons, 1 sedan) and put about 200K on each fleet.

Sharon was hit by a drunk driver and her 744 sedan performed well - she and her 3 friends were un injured. The trauma center could not believe that she was unhurt when the EMTs told them how serious the impact was right on the drivers door. They x-rayed her legs and hips because they thought she may have been so hurt that she might be paralyzed.

We loved all these Volvos.

It was apparent that the 850s were a much more modern generation - smoother, faster, better handling, more comfortable. We had 4 snow tires on all our cars and all did well in snow.

850s are harder to repair yourself - we used a dealer - parts and labor was more, but of course the 850s were owned later.

If I had a time machine, I would be happy to drive either.

We (my wife and me) now have two XC70s and they are great.