Since we have downsized to a single vehicle, there have been a few times in which we truly need two cars, and we are forced to make an increasingly expensive car rental. A zipcar model might not work as an alternative in Newton, but what about a community car sharing program? For example, we won't need our Subaru Forester during this August. But we could really use an extra 5-seater this July 7-9. For drivers with demonstrated clean records, it shouldn't be too difficult to set up a low-cost supplemental group insurance plan. Any insurance experts out there?