Yes, I too ride a Bike and I take your point. On a bike though there are no heat restraints and door pillars etc. I have worn a helmet before in a car and found it very tedious because you have to lean forward so that the back of the helemt doesn't catch on the seat and you end up looking at the inside of part of the lid, I also found that after a while my neck muscles where gettting very tired. I prefer not to wear a helmet in the car but I don't think there's any law against it.