I've been having great success using Condi (Previously Mini Tasker)
You can have it turn on/off bluetooth and open an app when the GPS senses you're driving. You can also have it turn things on or launch apps when plugged in. I connect my phone to a charger in the car (keep in mind I have the Mini, I am envious of your batteries) so, I have it automatically turn on Bluetooth when charging.
Time flies like an arrow, fruit flies like a banana. - Groucho Marx
Life, Liberty, and the Pursuit of Bacon!!!