Carbon dioxide from automobiles is a major contributor to global climate change. In "Virtual Rewards for Driving Green," Josh Pritchard proposes a computer application that will enable fuel-efficient drivers to earn "green" dollars with which to buy digital merchandise on the Web. Can getting items that exist only in cyberspace actually change a person's driving behavior? Pritchard, who notes that people are spending billions of real dollars on virtual items each year, is currently developing an app called Green Wheels to find out. (Contains 1 footnote.)