Update! Update!.....after a 5 sec search on the WWW , this article about just a few of the studies that have been done concerning this o' so important matter. One such study of the American country revealed that...
"In the USA, an increase in helmet use from 18% to 50% of cyclists over a decade was accompanied by a 10% increase in head injuries."
My experience over 50 years of touring, cruiser, sport, standard, cafe, adventure, motocross, scooters, mopeds, paragliding, and hang gliding and the many crashes and injuries experienced through these activities leave me with a few realities on using a helmet; there are more appropriate types than others for certain activities. How it is worn is crucial. Kevlar isn't that big a deal- a full face cracked in half hitting on the front guard part of it though probably saved my life left me with a neck injury for years.. Most crashes left my neck wrenched, soar, or injured due to the helmet - it tends to grab onto things and get stuck or dragged due to it's weight, design, size. Crashing when drunk at 65mph without a helmet not a scratch. Overall, I'll wear them on a longer, faster riding. Locally under 40mph I don't. Doesn't matter where I am. Though the link doesn't talk about using a helmet in a car, it does say more helmet use on motorcycles led to more dying. So next time, Kwilco, don't be a saphead booby and listen to Brn2Trvl. https://www.cyclehelmets.org/1052.html