From my brief research online, it appears to me that an “auto rosary” is a decorative rosary intended to be attached to a visor or rearview mirror. While it likely can be used in the same way any other rosary is used while at rest stops along the road, one should consider whether or not it is prudent or safe to dangle anything from a visor or mirror that could obscure a driver’s view of the road. If you need a travel rosary, you might try either a one-decade bracelet rosary that you can wear on your wrist, or a one-decade finger rosary that can be stuffed in your pocket or purse when not in use.