Quote (brmv @ Feb 26 2013 09:01pm)
probably mistreated before you got him
and there is very little you can do about it now
(should have been addressed when you got him)
Not helpful.
How is he around other dogs? I had a similar (albeit less intense) issue with my Husky mix (Link). He was skiddish for the first 8 months or so after we adopted him. We noticed that he really came out of his shell around other dogs, and acted completely differently. After locating a dog park near our house, and coaxing him to go his personality began to soften...rapidly.
Initially you're going to need to do some work to have your dog venture around your house and trust you enough to accompany you on a car ride, but the idea of play might benefit your dog. That being said, he might not have the motor of some younger dogs, so pay attention.
Also, If you have a close friend or family member with an older dog you know to be docile it might be nice to bring them around yours.