I found the reflectivity of the red reflectors on the Vespa top case was very low at night.
A c/d (cheap & dirty) fix was to use some chrome spray paint on the under panel, beneath the reflectors.
The reflectors are easy to remove, with only 1 screw, washer and rubber bump to be loosened/removed in order to free them.
Once this is done, simply mask off the rest of the top case and spray the under panel, let dry for an hour or so, then re-install the reflectors.
The night time reflectivity is increased quite substantially.