Handmade Brass/Bronze rosaries and car rosaries. The car rosaries are for decoration purposes only. Please check with your state as to the legality of hanging one from your rear view mirror. Having said that, even though I am not a practicing Catholic, I have a rosary that I have modified so that I can take my rosary, to see it and enjoy it. I have been in a horrific car accident that had a religious connection to it, so this is why I have mine hanging from the car rear view mirror.
I pray silently while touching my lovely car rosary every time I get into my car and start my travels. I have felt protected by having mine in my car. I give thanks to all my blessings at the end. To me it's my connection to God when I'm traveling.
No they are not blessed as that is a personal choice.