This may be the most important exercise you will ever teach your dog.  This one behavior could save your dog's life.  Dogs that bolt through doors and gates can be hit by cars, especially if they bolt through car doors.  Hatchback type vehicles are particularly dangerous if your dog has a habit of bolting from the vehicle the second you open the door.  I always teach my dogs, rescues included, to wait or pause and look to me for direction before walking through ANY door, gate or passage. 

Start with your dog on leash and walk toward your front door.  When you reach the door, tell your dog to wait then open the door.  If your dog starts through the door, close it and turn and walk in the opposite direction and say, "Oops."  Repeat this until when you open the door your dog looks up at your for direction.  That is when you praise the dog, offer a treat, say, "let's go," and walk through the door.

Please note that with this exercise the dog may be standing, sitting or laying down.  The only thing that matters is that the dog is looking up at you for direction on what to do next. 

Be sure that the dog does not go through the door ahead of you.  The dog should remain at your side or behind you.  Remember, you are the leader.  After you pass through the door, ask the dog to sit.  This will encourage the dog to wait for permission and then walk calmly through doors and gates.

If you do not use a crate when transporting your dog in a vehicle then he should be wearing a seat belt specifically designed for dogs.  In addition to keeping him safe while traveling, this will prevent him from bolting from or exiting the vehicle when you do.