Last year, after much soul-searching, I decided to trade in my trusty 1998 Toyota Avalon in favor of a smaller, better-for-the-environment car. I’d put about 150,000 miles on the Avalon and she was beginning to seem a bit worse for the wear. I traded in my Avalon for a 2009 Toyota Matrix, a car I’d been coveting since my cousin got one a few years ago. It’s much smaller but with a hatchback that provides excellent cargo space and it gets better gas mileage. According to Toyota, the 1998 Avalon gets 19 miles per gallon city and 27 miles...