I have found an old French book with plans and building instructions for many projects, from bicycle sidecars, velocars to small motorized sportscars.
Somewhere in the book I found a two seater velocar, wich is quite similar to my project:
Then it was simply the lack of alternatives:
Almost no cars at the market, no gas to run them and just low tech materials available (mostly wood).
Nowadays it's more a fun thing for persons, who are not pleased with all these usual high volume products, and instead build themselves an unique piece of craftmanship, which cannot be found elsewhere.
Happy New Year,