In this video Pete Mills demonstrates his blueShift project, an OpenXC LED tachometer he is working on:
An Arduino, some addressable LED’s, a bluetooth module, code and a 3D printer come together to make blueShift – An OpenXC LED Tachometer. blueShift is so named for the Bluetooth protocol used for data communication, and the use of a tachometer to indicate when to shift your car. It may be amusing to note that the driver and passengers traveling in this car would observe Blueshift when peering thru the windscreen, provided their velocity was sufficient.