I guess you are right, I cannot say with 100% certainty that the helmet saved this guys life but he was hit from behind by a car doing 40mph/64kmh and thrown 40 feet/12m and blacked out. He didn't post pics of the car but that helmet is pretty messed up and so is the bike, clearly a lot of force was in action here. I'll cut 'n paste his post just for the hell of it:
Originally Posted by Some guy
I got hit by a car.
I was riding up through Portola Valley and came around a turn when she smacked me from behind. She was going 40, me 15. I bounced up onto her windshield, broke it, hit my head on the passenger side bar, and as she slammed on the brakes I was thrown 40 feet, landed on my left side, and skidded for about 10 more feet. Ruined my bike, my favorite pair of Assos bibs, my Giro Atmos helmet (saved my life, for sure) and the paramedics cut off my jersey, gloves, and arm warmers (I get cold ok). Amazingly, I survived with only some bad road rash on both my knees, bad bruising or hematoma on my left shoulder/arm, some smaller abrasions to my face, and 4 stitches just below my left knee. All I really remember from the crash was a very very loud bang and then waking up later to the paramedics telling me not to move my neck. I spent 6 hours in the emergency room at Stanford,(I picked the right place to get hit by a car, that's an excellent hospital) and less than a week later (this was on Tuesday), I'm back on my feet, hopefully back on the bike next week. I feel pretty lucky that I escaped with such minor wounds, especially with people telling me about the damage I did to her car. Always wear a helmet, that's what I learned.