Good news is that he did come back when you called him and did not attack your dad. For the car, I would either crate him in the car if there is enough room or get a seat belt harness so he can be restrained when you are driving. This is a different type of harness than the gentle leader harness which cannot be used for restraint. Then start the training. Park in busy area and sit in the back with him at first. There are several threads on this and I do recall some of the suggestions was to use a spray bottle of water when the dog acted up, treating the dog when the dog was quiet - even just for a second so as to reward the good behavior. For the walking, he needs to focus on you and also not be allowed to lunge. If you look at it from your dog's point of view, when he is out for a walk - he is on a hunting expedition. Your dog is young - he sees something to lunge at or run after- he does unless you have him under control. So I suggest, you keep him fairly close in the heel position - the gentle leader harness that you use will help with this - leash in both hands - when you see someone approach - turn - even if you have to bump into your dog - when he follows - praise and reward. Then in a quiet area - let him he go "easy" on a loose leash and sniff and potty. He needs also an outlet for that prey drive and he needs to associate you with fulfilling that prey drive. Play tug with him - and after a good struggle - let him win - praise him - reward him when he brings the tug to you. He needs to bite down - he needs to "hunt". As you give him an outlet for that prey drive and keep his attention on walks, and work on the car manners, his behavior will improve.
Sting Chance von Gaard AKC GSD 2/8/2006