Pnolans: "In fact, your comment on borderline epileptic is something Ive considered. I was telling the most recent vet that it seems almost like "pre-seizure" symptoms ( I don't know if I made up a term or not). I had a dog once that started having epileptic seizures, and the "treatment" was one of the barbituates... What is so confusing to me is that when we're on a road that he doesn't like, as soon as we pull off, he calms right down... Sometimes, very rarely, he will stay nervous for a minute or 2. This is often solved by just pulling off the road and finding a place that both dogs can just run around."
As Dr.Jean mentioned, he might be picking up a stress odor from you. Has the dog ever ridden on the freeway in another person's car w/o this panic attack? Specifically without you in the car.
Some human epiletics can have seizures set off by flashing lights and other 'sensory overloads'. I wonder if there is a sound or something that is setting him off? Dogs can hear frequency ranges about twice that of humans, and can hear four times as well.
It might be worth asking your vet to prescribe a month's worth of epilepsy medication, and noticing if it makes any difference. If it does change things, you will also be aware that the dog's condition might advance to obvious epilepsy in the future.
