WELCOME!! sounds like you have done a lot of things right in raising up your dog!! and i gotta say, there
is something kind of cute about this behavior, although, i can see how you don't want it.
wow, i should not be trying to help you, as i do have a similar thing, with my dog-aggressive dog barking at other
dogs out the window,
but, i kind of think a DA dog's behavior is a lil different from other dogs behavior in some ways.
I bet you can solve this.
Do you use a "clicker"??
You *might* find using a "clicker" for this could help. (cost about a dollar or two at any pet supply store, or, you can buy them online).
This might be one of those things that you will have to try a few different things to hit upon the best one for your dog.
One thing worth trying, (this might not work to solve the problem, but no harm done either)
maybe the easiest of all,
is teach your dog to lie down on cue.
CLICK/TREAT. Reward this heavily.
Now bring dog into car, give "lie down" cue, reward heavily in a calm voice. You won't want to add to excitement at that point. CLICK/TREAT.
(car is parked in your driveway).
Now have dog in car, have someone dog KNOWS approach car, give "down" cue,
reward super heavily,in calm voice, CLICK/TREAT, and be generous with praise, have the person give dog treats, too.
Practice this for a few days.
Now, up the ante,
maybe have car door open, and you are standing in open car door, to throw dog off his game(?) if you feel confident your dog won't attack, have dog wearing his leash, maybe buckle leash to seat belts to be sure stranger is safe,
and have stranger approach car,
and stop about 20 feet away, give 'down' cue, reward and praise heavily.
Overtime, have stranger come to within 10 feet of car,
repeat,
with goal,
that at that some point,
your dog will become desensitized to the sight of ppl approaching his car.
closer,
and closer.
Now, have a family member in the car,
(since your dog
only does this if a family member is IN the car)
and you stand beside open car door.
Have stranger at distance, so dog is not yet set off, and give 'down' cue, and reward that.
Over time, shorten the distance, slowly, teaching dog you want him to lie down on cue, even if a stranger is somewhat near the car which holds a family member in it.
Set him up for success, have stranger at whatever distance your dog needs to not react, then overtime, shorten the distance.
CLICK/TREAT non-reactions. Keep visits of strangers close to car very brief at first.
YOu could also try giving the dog a yummy kong to chew on, to focus on, instead of the stranger near his car, while he is learning how to be calm in a car.
You can also offer dog calming signals, so far as i know, these only work
BEFORE your dog loses his mind (at least, that is the case for *my* dog). Dog has to SEE you do the signals, so dog will have to learn "Look At Me" to observe you doing
~slow, obvious blinks to dog
~one yawn
~a deep slow exhalation of breath out through your nostrils.
^these are 3 ways of saying "calm down" in dog language.
so far as i know, these are useless once the dog
has lost his mind, though. Have to be given before the dog gets upset, for my dog anyway.
If dog is NOT barking, stranger can toss treats to dog, too.
Scolding dog won't help even slightly, as dog may even think you are all joining in
on his being upset about this guy by the car.
Plus, dog is already out of his mind, now focusing only on his barking, etc.
this may or may not work.
Then, overtime, you up the ante more, and now car door is closed,
and then, advance to you are no longer standing by open car door,
nor by close car door, and are now sitting in driver's seat,
and so on.
there may be other ideas and better ways to solve this, and each dog is unique, but don't give up!!