I found more images from the
Fusion vehicle (Morelli's shape "bike" 4 seats), including photos of the earlier version with 4 wheels :
Note how in the 4 wheels version the front riders are not so close to the front beak as in the 3 wheel version :
The 3 wheel. See how the shell is thin and the weight it's mostly probably for the iron body for the riders and pedals :
Is that possible today to use thin iron skeleton reinforced with carbon fiber around the metal strips, to get a very lightweight skeleton ?