2. Avoid screens
Look, we know screens could potentially make life easier for you on a long car journey, be aware that for kids that are prone to car sickness, screens should be a big no-no. The images from movies and video games (particularly those with fast-moving graphics) create excessive visual stimulation that can confuse a kid's perception of motion and bring on symptoms. Note that reading may also cause a sensory disagreement, so you'll be better off letting your kid listen to audiobooks or an iPod, or playing car-games with you, such as the aul' classic "I spy."
3. Timing is everything
If possible, it's a good idea to schedule car rides to coincide with your child's naptime, since visual cues aren't sent to the brain when he's sleeping. For longer car journeys, travelling after dark is another smart strategy, since it eliminates most of the visual signals.