There is always a possibility that the Andean passes between Chile and Argentina will remain snowblocked and closed through the whole winter down at Santiago/Mendoza. However, they are probably usually open in the far north. The route from Arequipa to LaPaz past Lake Titicaca is pretty driveable, and snow is not much of a problem there. But I never drove it, but have been through there on a bus a few times. From LaPaz south to Argentina is probably still mostly gravel, but there are plenty of buses that go down there. Once you cross into Argentina at Villazon, the roads are excellent.
You can hunt for clues on YouTube, to find in-car travel videos of some roads, like this one, for the crossing Northern Chile to Argentina:
http://www.youtube.com/watch?v=8D5e9_c02uk
Looks like the road up there is paved, at least on the Chilean side.
I once tried to get from Paragay back to Santiago for a flight to Miami in August, and the pass was closed, I had to take a bus from Mendoza to LaPaz and pick up my flight from there. Flying back down in October, a woman on the plane told me it was still closed.