Calculating Force of a Side Collision: Help Appreciated

[BCole]

I am having some troubles figuring out how to calculate the force that the driver receives during a collision, I understand the physics of a car hitting a wall very well. but I have troubles calculating the force received when hitting another object in motion, not in a head on collision, but hitting the passengers side door. . any help would be appreciated.

 

[haruspex]

If you suppose the cars to be equal in mass and compressibility, it would be like hitting an unyielding wall at one half the speed.
That said, computing the forces is not trivial. Modern cars are designed to absorb impacts by collapsing at a fairly constant resistance, so, after the first metre or so, you can maybe take the force as constant. Then you can divide the KE of the driver by the stopping distance. In practice, the force will tend to rise during the impact.