everything in a production car is designed to bend and fold in a certian way, to absorb energy, lessening the amount given to the driver. A 5 point harness is no good unless you ancor it to a roll cage and a roll cage isn't any good unless its properly secured to specific points in the car. and a driver strapped to a seat w/ a harness in a roll cage dose not absorbe much energy in a collision the driver will take a lot more and increase the risk of fatal injury unless your in a race car with a helmet, teathers, coller, hans device etc.
There is no way of testing real world crashes, My dad is seniour product investigater and product expert for General Motors Canada and works with this stuff all the time, I've seen a the reminants of a fatal accident with a chev traker there was maybee 200$ worth of damage, just a fender bender but the guy wasn't wearing his seat belt and hit the corner of the windshield frame with his head and broke his neck!
My advice would be don't buy anything chrysler they're "cab forward design" dose a fantastic job of crushing your legs and pinning you in the car, alot of the fwd cars are excellent in crashes you as the driver just have to be carful!