Hi Gary
I have used Bach flower waters in the past when I first started showing one of my dogs. He used to get a bit nervous believe it or not (six months onwards). I just put a few drops on his tongue 15 minutes before we went in. I'd say it worked.
You can get all different types for different problems. I used Larch. Rescue Remedy is the most popular and comes in droplets or spray. However, I believe you have a training issue on your hands which will need a little bit of work.
Regarding your dog, make sure he's secure and can't freely move around in the car, I use dog car harnesses or seat belts. Secondly, when you are about to put him in the car, do so without any fuss whatsoever. I'd take him out on dummy runs to get him used to it.
There is a process where you put dog in the car, start engine, if the dog whines etc, you take it out of the car and back in the house and so on and so on. I do know people who have used this method successfully. You must remain calm and confident throughout.
What ever you do, don't praise or reward unacceptable behaviour (whining and yapping) by acknowledging it through voice and inappropriate body language.
Hope that helps.
Lisa