Brecon Beacons, Wales - I can't stop looking at this photo! Amazing landscape with beautiful colors, the sunset and the green fields are touching my heart! It's is sad that there aren't many photos of Wales on Pinterest. If you have, please share them!
Resting the camera on the dashboard of the car to keep it relatively stable would be a good approach. Then it's just the car's movement and the cars outside that will create the blur and not camera shake. This will have to be experimental as far as shutter speeds and exposure are concerned. Obviously night time would work best if I am going to record light streaks. The camera pointing at back seat and kids with blur outside?