Reed:  However, it does not matter.  Impacts  at 20-55mph can be devastating.   Several years ago I was stopped at a light.  I was in a 1 ton p/u truck  and was rear ended.  The driver that hit me told police that he was going 35mph.  It was a tremendous impact and shoved my truck thru the light and into another vehicle.  My airbag saved me from serious injury.  My neck got pushed out of joint and a chiropractor got it back lined up. No problems with the neck but $20,000.00 dollars as a settlement is not worth going thru all the trips to physical therapy, paperwork, dealing with insurance companies etc.     People just do not realize what a  serious impact it  is at lower speeds unless you have been thru it.   That vehicle they are building is a DEATH TRAP............