You could try Rescue Remedy, which you can buy in Boots and other chemists. One of my Cockers, Sam, was a terrible traveller and used to whine, dribble and throw up after about 5 minutes of car travel and would remain whiney and stressed throughout the journey.
Someone suggested Rescue Remedy, so I tried giving him 2 drops direct onto his tongue about 20 minutes or so before a journey and it worked like magic from the very first time. After a few weeks we stopped using it and he was fine because he was so much more confident and relaxed in the car.
It doesn't make them sleepy, just helps to relieve stress. I take 4 drops before I go to the dentist!
