I've been a bike helmet devotee since I was in college 40+ years ago.

My one roomie was riding with his buddies (behind them) in 1975. Car saw the other riders go by, then backed out of the driveway in front of Jim. He hit hit the car broadside and flew over, then skidded down the pavement another hundred feet or so... Thankfully, he was wearing one of the original Bell 'mushroom' helmets, and the helmet got ground through on the side... That would have been his ear/side of skull. Good enough for me.