Whilst checking where in Spain Benisa is I happened on this: https://www.scootering.com/scootering-classics-spanish-hideaway-part-2/ I’m not into scooters myself, but there are a lot of small Ducati etc. in there too.
If I remember rightly, in France in the 70s, you could ride a moped at fourteen, but had to register it at the local Department: much less formal than cars and trucks. I wonder what the arrangements were for small bikes in Spain back in then?
I'm pretty sure before transport become so massive that some of the european countries had regional number plates rather than national ones
It's the size of a credit card so I doubt it - no I am not sure but shut up as I'm looking as though I know what I'm on about for once ...
I have sent the plate photo to a mechanic I use here in Spain. He rebuilds vintage bikes, so he should be able to help.