Back in 1981 my next door neighbour had a fold up 50cc bike, it was badged as a Britax but I would have thought it was actually manufactured in Italy and imported/sold by the seatbelt manufacturer (dont they now make kids buggys?) it was kept in a holdall, and you could carry it a short distance – he used it as transport when out and about on his narrow boat. I did try it out and it had extremely sensative steering due to the small diameter wheels.