As an inner city insurance agent, I disagree with these findings.
In my neck of the woods, everyone gets whiplash, be they in a Honda or a Hummer. Severity of injury is directly relative to the speed of the "runner" in contacting the accident victims.
My favorite was an elderly woman who had a wreck, went home, called me four days later and burbled, "honey, I didn't even know I hurt til this nice man called me on the phone this morning and told me I did!"