I was talking about the kind of helmets bicyclists wear. The only thing a bicycle helmet would save you from in a car wreck is hitting your head against the windshield/dash which is what we have airbags and seatbelts for.

Also, race cars aren't really comparable to normal driving situations since they go much faster and have a different set of constraints than normal cars. The racing helmets, rollcages, and 5 point harnesses aren't really as necessary at 70mph as they are at 200mph