VOLANTE
It as the looks of the 'Volante'. Developed from 1976 onwards and intended to be produced as a kit for home mechanicals. Wings, front stubs and propeller are all removable (as in your picture). I have a picture of the prototype WITH these items on (see attachment) .Designed by K.P. Rice, with an aircooled four cylinder VW engine, 75 HP, placed behind the cabin. Calculated performance 130 mph in the air, 70 mph on the ground. It was licensed in California as a motorbike and it received an experimental FAA airworthyness certificate.
I suppose this prototype of my picture is the SAME VEHICLE as yours. ou stated it is European, it roots are from California. My source didn't state that the kits were actually supplied. But if so, an European builder made his own version, with mechanicals to his own choise.....