I would like a way to have my car automatically lock the doors if I accidentially leave the car with them unlocked. For example, I pull into a spot, get out and leave the car unlocked. 30 seconds later, the car locks itself.

Is this possible on my 2008??

 

Have you checked your owners manual? There should be a section for programming key fab and door locks. If it is possible it should be outlined in that section. Good luck.