Dreamcatchers and Rear View Mirrors

I’ve noticed small dreamcatchers hanging from the rear view mirrors in cars.  For those of you who don’t know, dream catchers are circular, round, look like the circumference is made of wood while the interior looks sort of spider-web-ish.  Then you can decorate them with feathers and stuff.  Chippewa Indians intended them to catch dreams and let nightmares slip away.

You dream when you sleep.

You don’t normally sleep when you drive.

What are dreamcatchers doing in cars?