Hmm as a 2CV and GS (yup, thats the model, not the trim level) owner for a number of years, I had always believed the the "two horses" cam from the original design spec given to Andre Citroen. he wanted to create a vehicle that would replace the standard farm buggy, which was pulled by two horses, the suspension was to be good enough that the farmer could (if neccesary) drive across a furrowed fieid without breaking a basket of eggs. A slightly different design spec than that used today, but it worked!
As a point of interest, i live in WesternAustralia, and we have a "road" called the gunbarrel highway. this streaches from a point about halfway up Western Australia and travels straight across to Alice Springs (The town that the famous Ayers Rock is near) it was last graded (leveled) in the late 60's and has been used by various adventurers to demonstrate their offroad ablities. Typically it is Kms of red dust and potholes, some as deep as 4 feet. About 8-10 years ago we had a "Raid" of 2cv and Citreon enthusiests from all over the world. we did the gunbarrel, and the only vehicle that got seriously bogged was the Nissan Patrol Support vehicle!
As another point of possible interest, the 2CV in the james bond movie was actually a "production" car. it was called a "Sidewinder" it was basically a 2CV body mounted on a GS chassis and motor. They used to go like a cut cat and supposedly could take a porche at the lights, perhaps the shock factor helped though. :-)