Yes, I think the blue notch is the prototype that normally sits at the official VW museum in Wolfsburg, dont know about the cab...lets hop for some help from our german friends...
/Lars
-914/4 -72 daily driver
-Husqvarna 120cc rat bike -48
-Husqvarna 120cc -52
-BMW 600 Road Scrambler -69
-Suzuki T500 Cobra -69
-VW411LE 2-door sedan -70
-Porsche 914/4 -72
-VW412LE 4-door sedan -73
-Suzuki K50 -77
The red convertible is also from the VW museum and is the one and only build prototype. Our dutch chairman from the VW412club Holland had the honour to bring it from the museum to the techno classica in coorperation with the german club.
The blue one is a prototype type4 "notch", but because of the fact that there was also a type3 notch this car didn't make it to production stadium.
Nice fact: it had only 196 km driven.
i get laughed at for owning an ugly car... but i do not care... \I love the whole look of the 411...
We all share the same madness dude...
According to the text on the website and what I can remember was the stiffness of the cabrio a problem. Solving that problem would lead to a (to) high price for the car.
So i think the VW factory wouldn't dare to take that risk. And besides that they had already 2 cabriolets (Beetle and karmann).
In my memorys there was also a karmann type 34 cabrio prototype that was never been launched, but I'm not shure about that.