Obnoxious Car Behavior

Question
My 5 year old GS is my best friend. He is great around the house, sweet to
kids and old people, and extremely smart.  He is trained fairly well but still
exhibits some stubborness and tends to be dominant.  I have responded with
tons of love and reinforcement of good behavior and that has worked for
most of the issues that have come up over the years. I should mention that he
and I are both 130 lbs and he is much stronger than I.  I count on his good
nature and training to keep him under control and we've never had a
problem.
So things are great except for car trips.  I drive a station wagon and he rides
in the back with a dog seatbelt.  He shrieks and whines constantly while we're
driving and struggles to get in the back seat. He used to quiet down after
about 20 minutes but on our last drive he whined the entire 2 hours. I think
he wants to be sitting on my lap while I drive! I don't want him to destroy my
car.  I used to have a barrier but he would spend so much time scratching and
biting at it that I was worried he would chip his teeth and so I removed it.
I have the air conditioner blasting at him the entire time (because he shrieks
louder if I don't) and he has plenty of room to stretch out.  I also stop
constantly to let him go to the bathroom--I need to let him out far more
often than when we're at home.
I am about to go on a 6 hour car drive with him and a friend and I don't want
him to ruin our trip.  Can you suggest anything that would calm him down in
the car?

Answer
I doubt there is much you can do very quickly except ask the vet for medications.  It really sounds like even if he obeys his commands, he is still in charge.  You need to take over.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

Once you are in charge, you should be able to command him down and stay in the car and he will comply.  You may even have to go through a stage of having somebody in the back seat, or letting them drive while you work with him.  As old and set in his ways as he is, it will take a long time.  We often have a 5 hour drive home with a 7 week old puppy.  By the time we get home, our puppy is often better trained than may 7 month olds.  It is so much easier to start right, then try to fix problems at 5 years.