How do I have my Galaxy S3 automatically switch into Driving Mode when I am moving in a car?

It seems like I read something about how to do this once, but now I can't find it. I thought it was a feature of On{x} , but it doesn't look like the *Galaxy S3* **Driving Mode** is exposed through their API. What I want is for my phone to automatically switch into **Driving Mode** when it detects I am moving faster than a certain speed (doesn't need to be immediate), and then when I am moving below that threshold switch back (again, after about a minute).