Front space is actually pretty decent, so even if you’re tall you’re unlikely to struggle for head, leg or elbow room. You’ll probably find the pedal area a bit cramped if you’re shod with anything bigger than size eights, though.
How much space there is in the back depends how tall the driver is, but an average-sized adult should fit by splaying his or her legs either side of the front seat. Alternatively, the Twizy Cargo replaces the rear seat with a 180-litre boot for extra luggage-lugging ability. The maximum payload is a reasonable 75kg.
The standard Twizy has a meagre 31 litres of luggage space (under the rear seat), plus a pair of modest gloveboxes. Renault would argue, of course, that this is much better than the storage space in most mopeds.
The gloveboxes and under-seat compartments are lockable, but the lids are rather flimsy, so we wouldn’t leave anything valuable inside.