and, Annie - it is French again!
But, it is wonderful as all of ancient pedal-cars. I suppose that they were kid-cars and used on privileged surfaces (parks, private or public and so on), so simple wheel shouldn't be problem. Beside, it had good springing at the rear. I think that pedaling wasn't so easy with such position of seat and pedals - legs couldn't be stretched enough. I had such experience with promenade-carnival quadricycle (when I was young) - quite terrible. Making it bigger shouldn't be problem, using wood or metal for chassis, even a lot of components from my present quadricycle. It has now 52 kg ~ 115 pounds. With careful constructing, new one shouldn't be much heavier? With light engine - still a lot under 100 kg ~ 220 pounds. With two persons pedaling it could be movable up to 15 mph and with engine even more? Of course, not for highway or any unprotected areas.