@all-who-agree-with-the-crumple-zone-logic (Y)
Front crumple zones need to absorb the impact specially because the car which rear ends delivers retarding force (to the passengers) in opposite direction (to which it is travelling) than the the car which is rear ended delivering force in the same direction as its direction of travel
Hence, the more your car is compressed the lesser retarding force you get;
As you know v^2= u^2+2as
Here v=final velocity is zero and u=initial velocity and a=acceleration (or retardation in this case)
so u^2=2as
u=70 km/h =19.44 m/s= but lets say just before impact the braking reduced it to 50 km/h=13.89m/s
and S= distance travelled during retardation (amount by which car is compressed)
if S is small, a =retardation is large
if S is large, a =retardation is small
and retarding F=mass x acceleration (or retardation in this case)
so do the maths yourself...
Also Toyota does spend a lot on R&D ...
lot more than its rivals.... No names...
check out yourself... Numbers speak for themselves
see
http://www.spectrum.ieee.org/images/dec07/images/12.RDchart.pdf