Folks, you have to understand the tests:
40 MPH Fixed Barrier and OFFSET
The latter means it only impacted on a part of the front of the vehicle. Larger vehicles tend to do worse because of the Total ENERGY (Force) that must be dissipated across a small section.
F=M*V2 where V2 is the Velocity squared.
Bigger vehicles have a higher Mass (weight).
Also Note this was the OLDER body style F 150 not the new one.
Troutly also is correct in pointing out the survivability of a 40 MPH is far less than the 35 MPH standard currently in existence.