The EconoDriver and SafeDriver by Lemur are wireless vehicle monitors that record driving performance to a key fob display to help drivers be more efficient and safe.
The key fob displays are battery powered and can be mounted on the dashboard for continuous monitoring of reports. Both units ship with a sensor that plugs into your vehicle's OBD-II port to wirelessly transmit information from your vehicle's sensors to the key fob.
The SafeDriver displays the maximum speed, distance traveled, and sudden braking incidents to help parents keep tabs on new drivers. The device locks with a PIN to keep misguided youths from simply clearing the memory after a crazy night out. Meanwhile, the EconoDriver displays average and instant fuel economy, and a green rating. After plugging in a fuel cost, the EconoDriver can also display cost per trip and, if you're feeling particularly masochistic, the cost of fuel wasted by inefficient driving.
Lemur also offers a product called the AlertDriver, which is another OBD-II-port sensor that simply monitors vehicle speed and sounds an audible alert when 70 mph (or a custom max speed) is exceeded. The AlertDriver does not include a keychain display.
The SafeDriver and EconoDriver retail for $69.95 each. The simpler AlertDriver is $49.95.