If you own a car that was built after 1996, it has a something under the hood called a diagnostic port. Your auto mechanic plugs his computer into the port so he can test the various systems in your car and determine why your "check engine" light is on. Diagnostic ports haven't been much use to car owners themselves, unless they own the same sort of elaborate equipment that garages own. Recently, however, a Canadian company called Lemur Monitors began marketing several data port devices that drivers can plug in for entirely different uses.
One device, the SafeDriver module, monitors the highest speed that the car has been driven and how often it has come to a sudden stop -- a great way for parents to see how their teenagers behave behind the wheel when they're driving by themselves. Another product, the AlertDriver, can be set to sound warnings whenever the car is being driven above 35 miles per hour (56.3 kilometers per hour) in the city or 70 miles per hour (112.6 kilometers per hour) on the highways. A third device, the EconoDriver, enables you to analyze your gasoline consumption and see whether you're driving as efficiently as you should [source: Taub].