Inflated Car Seats

Car seats that are air bags as well.  Just like the sleep number bed, chambers could add support without it feeling like you are sitting on a balloon.  There would need to be a valve that would release the gas when the pressure exceeds a certain amount.  When a car is rear-ended and the passenger is pushed back in the seat the pressure would increase triggering the gas to be released through the valve.  The release of gas would cushion the passenger and prevent whiplash.