Mine pairs automatically every time I start the car. It definitely should do that.
What unit did you go with? I'm wanting to change mine too. Someone rear ended me the other week and I had a hire car replacement while it was getting repaired, and I swear the newer units with their bluetooth audio capabilities just made it so much clearer how inferior the stock head unit was. Although truth be told, the head unit was always the biggest disappointment for me when I bought the Presara new back in 2010. For the price you had to pay for the model, the head unit was ***** poor.