This palm-sized computer measures a car's acceleration, horsepower, torque, and more, allowing you to determine if the vehicle is achieving its optimal levels of performance. The 4 1/3" color touchscreen displays customizable gauges that measure 1/4-mile, 1/8-mile, and 0-60 mph times, and determines the braking distances at different speeds with the touch of a button. You can monitor the car's fuel economy and see how the miles-per-gallon data changes with different drivers. The device can save all measurements to an SD memory card (not included), allowing you to compare the car's performance at different times of day, in hot and cold weather, or if new tires or other new parts have affected its capabilities. If the check engine light is on, it displays and defines the diagnostic trouble codes that are causing the warning. For hybrid cars, it monitors the vehicle's battery level and shows how driving habits affect the transition from electric to gas power. About the size of a GPS, the diagnostics analyst simply plugs into your car's OBD2 port under the steering wheel and mounts to the dashboard or windshield. 3" H x 5" W x 1" D. (8 oz.)