My 4 year old was like that when he was born. I thought all babies loved the car. Mine cried all the time, long distance too... It was so horrible, I hated taking him any where. If I was the passenger I would take him out and hold him, which when I was with my sister or mother they would pull the car over until I put him back in his seat. One thing I did that could help a little, as I drove, if I put my right hand back so he could hold it, he would stop crying. My other kids would try to help me out and put their hand as if it was mine, if he was really tired from crying we could possibly get away with it. At the time I lived 5.5 hrs from my parents so long road trip were horrible with him, which usually took at least 7 hours if not longer. And yes, my arm usually fell asleep as I was driving, I could only do it for 15-20 minutes at one time, which isn't always the safest thing to drive like that.
He finally out grew the crying when he was about year and half. Loves the car rides now, he's 4. Not sure why he didn't like the car rides, switched seats everything, still nothing. My older two kids, love the car from day one. I used to drive around when my daughter wouldn't fall asleep to get her to go...
I know you pain and frustration, time is really the key or was for me. Never figured out what exactly the problem was, but he didn't like car rides. You would have thought someone was hurting him...
Hang in there!