Puff is a driving accessory: a device that visualizes the amount of pollution the car is producing in real time. The color of the lamp attached near the car’s exhaust changes dynamically. Green indicates the lowest rate of pollution, red the highest.
An accompanying iPhone app provides feedback for the driver, shows the number of pounds of CO2 emitted per minute and the total pounds emitted during the current trip, and keeps track of the user’s emission data over time.