Does anyone ever consider, I never did until a few years ago, can you imagine how hard it would be to drive an invisible car around, no one would ever yield to you. If you, in your invisible car, were in front of someone else they'd try driving right through you at a stop sign. Also if there were no other visible cars on a narrow road they would probably drive in the middle and in your lane thinking they had the whole road to themselves. That's why I always worry when the road is narrow, I try to keep on the right side, in case there are invisible cars. You can never be too careful.