What is this mystery bike?

[Henrik]

This is really interesting! As Cormanus mentioned, that would be a Puch, more specifically a VZ 50. It was a moped sold mostly across Europe until mid-70's. I remember as a kid in Sweden, the Puch Dakota (as it was called there) was a really popular moped as it could be ridden from 15 years. My brother had one, and as soon as I turned 15 I would ride it as well.

I never knew that they were also sold in the US through Sears though.