I've had a puppy for a few months now...a failed foster. He spent the first few months of his life in a crate with no socialization. His first ever car ride was when some stranger grabbed him, wrestle...
Great news! Keep plugging away at it - it will keep getting better. And don't lose heart if he falters in his progress a bit, just go back to the last point of no problem and start moving forward again. Sometimes a dog just needs to know you'll love him even if he does puke... :)