You're A Good Man Charlie Brown
The speed is important because it determines the amount of kinetic energy that must be dissipated in the crash. The higher the speed the more energy. In fact, the kinetic energy is proportional to the square of the velocity. So given a fixed vehicle mass, we can scale the energy dissipated versus speed. Squaring the respective speeds we get:
30 x 30 = 900
35 x 35 = 1225
40 x 40 = 1600
Examining the data, we observe that the amount of increased energy absorbed going from 30 to 35 mph is 325 units (1225 – 900). The ratio is 1.36 (1225/900) meaning the percentage increase is 36.1%. Similarly, going from 35 to 40mph is 375 units (1600 – 1225). This ratio is 1.31 (1600/1225). So the actual energy dissipated in the current test is greater in absolute terms than before (375 vs. 325) and starts from a higher initial point (1225 vs. 900). The engineering naif is prone to assume a 5 mph increase is the same whether you are going from 30 to 35 or from 35 to 40. He would be wrong! Note that the increased energy going from 35 to 40 mph is equivalent (375 units) to a 19.4 mph crash!
So Kia meets the government standards as written, but cannot absorb the equivalent of an additional 19.4 mph crash. Are you really surprised? Do you think that the weight saved might have been used to increase fuel economy? Which is more important to you, energy independence or the ability to drive into a wall safely at 40 mph rather than 35 mph? We report, you decide!
P. S. So my advice to Charlie Brown is this, if Lucy keeps pulling the football away, kick that which remains stationary, LUCY. She’ll learn really fast not to mess with a Good Man.