You mean a silly mirror?

Right. A helmet adorned with lights, reflective tape, and yes, a silly mirror, most certainly can aid in preventing a collision with a car! Of course there are other ways to mount this stuff, but a helmet is a pretty darn handy platform for this, and up higher than any other mounting location. Being able to turn and aim a headlight at drivers waiting to turn out can be particularly handy.

I actually think the above mentioned safety advantage of a helmet is more important than any tiny amount of "protection" a little styrofoam provides in a crash.

I wonder how long until this thread gets locked.