Buy the kind of helmet that has been shown to prevent concussion...... .........then also wear it while you're riding in a car since you'rer more likely to suffer concussion from that activity.

Everytime you ride in a car at 55 mph or even walk down a sidewalk without your helmet you're takign a gamble, which I'm not willing to do. My helmet is on everyday -- heck, even while watching Sunday football at the pub I won't take a risk.

Sorry -- impossible to resist hijack.