I think driving my car on the kind of ice we're discussing would be even less fun and even more dangerous, since I don't like being responsible for 4000 pounds of semi-out-of-control steel. My winter commuter is much easier to control on glare ice than my car, no doubt about that.

As for the original question, it sounds like it was a dangerous day to be out there, period. If the goal is to avoid getting hurt, being inside a Jeep stacks the odds in one's favor. If the goal is to be less exposed to potential collisions, it sounds like the bike was the better bet since a large chunk of the route had no cars. Personally, I'd ride, and would probably ride the biggest, most heavily-travelled arterials practical, since they get the de-icer priority, and get melted down by the auto traffic as well.