I would look around for aggressive dog classes, they are out there, but not sure any available to you.
Dogs can go thru funky stages, not saying this is permanent nor saying it isn't.
I personally, don't want my dogs loving every stranger they meet, however, they do have to tolerate and mind their manners when "I" am meeting/talking to, say, a stranger to them. Which means they are either in a sit or a down , and minding their own business
It's never to late to keep socializing. However, it sounds like you've got your hands full...The crazy in the car doesn't surprise me, many dogs are like this. My gsd is very quiet in the vehicle whether I'm in or not, but "touch" my vehicle and all bets are off. (IF she doesn't know you)
What do you do when he lunges at someone? I would have a prong collar on him and he'd get a correction. If he even "thinks" about it , I would use a good "leave it" 'before' it happens..
Is he treat motivated? Always have them on you, when you think your going into a situation where he's going to react, divert his attention, treat and praise..Change directions with him before he reacts..no reaction gets treated and praised.
A reaction, gets a correction..
I would get him back into some type of class/trainer situation pronto. He won't grow out of it without some type of training. Continuing behaviors with no consequences or training will continue..
Like I said, he doesn't have to "like" people, but he does have to behave himself, mind his own business and tolerate the presence of other people..He doesn't have to have strangers 'petting' him either..He just has to 'be'..
Good luck,,best suggestion, get back into a class/trainer