German Shepard Mix Fear Anxiety/car anxiety

Hello,
I have a couple questions about my dog. He is a german shepard lab mix and is just great! However, I am pretty sure he has fear anxiety when it comes to other dogs.
1. He barks and growls viciously at other dogs but I can tell that it stems from being afraid of them. I do have a thundercap but I am not sure if that will make him more nervous. Today he barked and lunged at another dog that was on a walk, and made the owner turn around (I was so embarrassed and felt so bad)
2. He has car anxiety and barks at every car he sees in the car and whines. I just bought the thundercap and have been training with that, just wanted to know if there were any other suggestions.
3. Motorcycles. Today he almost broke loose from me during a run to chase a motorcycle.
Any help would be appreciated!