My father had a Quickly in the 50s (not a Vin unfortunately). Since it was the only family transport he fitted a dual seat and footrests. Almost every time we went out, a cop would flag us down and say " You do realise it's illegal to carry a passenger without a ....... errrr ........ proper seat and ......... errrrr ......... footrests. Well, I've never seen one of those before, off you go." A short time after, NSU brought out the dual seat version.