You need to be careful. In Colorado we have the "Make My Day" law, similar to Castle Doctrine. It will shield you if you defend yourself in your home and fear for your life or personal harm. If you attempt to protect your property outside you house you can and will be prosecuted.
http://www.thedenverchannel.com/news/24231446/detail.html
I worded my previous post incorrectly (or at least misleading). You are both correct.
From my earlier post the Castle Doctrine does not allow you to “defend your property with deadly force” as I stated.
What I meant and did explain correctly is that you can intervene to stop a crime on your property per the castle doctrine. You can defend your property. If your intervention causes the perp to escalate the situation in which you are in danger of great bodily harm or death, you can defend yourself with lethal force if necessary.
The distinction here is that you may legally approach the perps that are breaking into your truck in the driveway while armed with the intent of stopping the theft. If they pull a gun or attack you instead of fleeing, you may defend yourself.