I raced Dirt track cars for a few years... you know the kind with cages and HELMETS! In my car, in a racing seat that basically hugs you tight with 5pt harness. A cage built for impact. Built for safety. Sitting in teh car, strapped in tight, I can not move at all without the seat moving. I can't hit my knees on anyhting but the inside knee protector, and my helmet will not contact any part of the roll bar. I didn't use arm straps, which could have saves a few sore arms. I've been in several wrecks though where my helmet smacked off a rollbar, my arms smacking off the door bars, and my left kneee smacking off the door bars. All things that I could not do just sitting in the car with just the force of my own will trying to hit them. My door bars had so much padding on them they looked like pillows, and there were still wrecks where I banged my left knee or arm (if I couldn't hold the steering wheel hard enough). times I had concusssions from banging my head on roll bars and couldn't walk half the week cause my knee was so bruised. Yes these were pretty violent crashes but what exactly do you think it's going to feel like if someone runs a red light and drills you from the side? aside from being T boned right in the door where you will likely be seriously injured with or without a cage, it's going to hurt bad or be fatal when your skull gets crushed by that round steel.