I want to make sure you get some help, so I'll go ahead with an answer with the limited information I have.
He has a few issues so lets approach them one at a time. First he definitely needs obedience training. this isn't so much to teach commands but to teach him that you are the boss and he has to listen to you. In addition, it also makes you the one responsible for protecting everyone and not him. That means you do need to keep other dogs away and not let them interact with him unless he initiates the interaction which he might over time. So don't just let other dogs come up on him. Don't make it obvious, just move a little further to one side so he is out of reach of other dogs. You can also walk him on the opposite side of you so he isn't on the side that most dogs are going to be on.
Teach a good walk on lead which should be right next to you. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
It will be helpful if you can find someone with a dog to help you once you have your dog listening to commands consistently. What you will do is have your dog on the leash. You will have your helper off in the distance. Your helper will gradually move their dog a bit closer to you preferably walking past your position in the distance. As long as your dog ignores them, you can give your dog praise and a treat. The second you see him fixate on the other dog or show any other sign of aggression (hair standing up, etc.) give your dog a correction by giving a short tug and a firm low toned "NO". It shouldn't take your dog long to realize you will not tolerate the aggression and that if he ignores the other dog, she gets treats. Once this happens you can repeat the training moving the other dog closer until he is no longer trying to lunge at other dogs. You will need to practice this when you and your dog are walking as well.
If your dog is walking right next to you and you are moving at a fast pace he won't have time to react to the other dogs as easily. The following site has another method of helping dogs that react to other dogs.
For the car issue, you might try a dap collar. They use pheromones to calm an anxious dogs and the whining might be due to anxiety. It might also be related to car sickness. Some people use Benadryl to calm their dog before car travel and Dramamine is also used for motion sickness, but your Vet should be consulted before using Dramamine.
Benadryl can be given to your dog, the dose is up to 2mg per pound every 8 hours. The dosage for Dramamine (Dimenhydrinate) for motion sickness is 2-4 mg/pound by mouth every 8 hours.
Any medication should be given an hour in advance to car trip. Give these techinques a try and you should see improvement within a couple of weeks typically if you are training regularly.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.