MPG Improvement: 10 to 20 percent A similar albeit simpler, less expensive, and easier to use version of the MPG Meter is the Fuel Mizer. The Mizer works by monitoring your driving under a set list of expected driving behaviors. If you don't follow those guidelines it gives you a little reminder in the form of a gentle alarm. If you take off from a stop light too fast... beep, or slam on the brake pedal to abruptly... beep. It also features a visual light scheme which detects the extent of your good or bad driving behavior.
A yellow light means you are driving moderately bad, a green light means you are driving pretty decently, and a red light means you better straighten out, otherwise you're about to get beeped. The unit itself is no bigger than a deck of cards and can easily be transferred from vehicle to vehicle. If you can get past the annoying critical nature of this beast, it actually can save you a lot of gas.