In response to Al's query of why Portland is not in the top 15 metro areas that use cars the least, here are Portland's statistics:
Car: 81.5% (9.9% carpooled)
Other: 7.1% (6.1% worked from home)
This puts Portland barely out of the top 15 (#15 was 19.2% non-car), but look at the area this includes:
If we look at just Portland, here's how the statistics change:
Car: 70.1% (8.5% carpool)
Other: 6.9% (5.9% worked from home)
That would put us at #2. I think the honest answer is somewhere in-between.
It would be interesting to see what these stats look like if you limited the geographic area to just the major cities (Portland, Beaverton, Hillsboro, Vancouver, Gresham, Milwaukie, Oregon City, etc).
Also, I would prefer to see the ratings include the carpoolers as non-car (i.e. instead of Car/Non-Car it should be SOV/Non-SOV).