Abstract
We use microlevel data on fuel consumption, mileage, and travel mode to study how plug-in hybrid drivers respond to fuel prices. When fuel prices rise, plug-in hybrids reduce fuel consumption more than gasoline and diesel cars. They do not proportionally reduce their mileage; instead, they increase electric charging. Since plug-in hybrids drive in electric mode for only half the distance suggested by official test cycle values, fuel prices are effective in improving the environmental performance of these vehicles.