Whining, prancing terrier/maltese traveler - help please

If he is loose, I'd try putting him in a carrier - a lot of dogs feel more secure in their vari kennels. They could also try some Bach Rescue Remedy. Works well in a variety of situations for dogs.

Hope they can find something that works. The constant prancing and whining can work on one's nerves after a while and also be distracting to the driver.