Had another thought.... unconventional as it may be, with out actually going for a drive, bring the dog into the car with you and just read a magazine or have a picnic, the car's in a garage so your neighbors will be none the wiser.
Something got your pup upset about being in the car it sounds like, maybe spending a little extra time in there with out actually going anywhere will let him know it's a safe place again.
Picturing the car in the garage, you, your pup, your wife, a bottle of wine, some cheese and crackers all in the car for a half hour, see how that goes. Just a thought.