Vision HUD is an Android application that uses GPS data from your device to calculate your speed with precision and prompt it to you as a speedometer into the screen of your device or an upside down image of it that can be reflected onto a glossy area nearby, such as your car's windshield. It supports MPH, Km/h and Knots metrics, shows incoming SMS messages on your car's windshield, has lots of colors and skins, is very accurate, has speed limit alarm (configurable) and other features.