SmartDeviceLink (SDL) is a standard set of protocols and messages that connect applications on a smartphone to a vehicle head unit. This messaging enables a consumer to interact with their application using common in-vehicle interfaces such as a touch screen display, embedded voice recognition, steering wheel controls and various vehicle knobs and buttons. There are three main components that make up the SDL ecosystem.
This app is a simple Bluetooth connection debugging tool:
This project contains sample code for Bluetooth communication.