Two days after an ice storm, which had deposited about 3 inches of ice and sleet in our area, we were traveling home on the highway. A minivan passed us. A sheet of ice released from their vehicle became airborne and hit our windshield at 55 MPH. We estimated it to be about 8’x4″x3″ in size, weighing 450 Lbs. Thankfully no one was injured.