The fourth and last Kamm car happened really by chance.
Apparently, a high ranking SS officer with a penchant for unusual vehicles offered Kamm a chassis if he would design the body. Kamm agreed and a BMW 335 chassis was delivered.
A model of the body was made and tested in the wind tunnel. This model still exists along with other wind tunnel models.
As World War 2 came to an end, the car's owner put the car into hiding. It was removed by French army officers and taken to Paris, where it was last seen in 1948.
There is a theory that it still exists somewhere.