actually "'Economica' was better equipped" is incorrect...
the Ecconomica was the lowest of the low, it was stripped of anything that it could be... they had no wind up windows, no chrome trim and even no rear Nuova badge, and no rear seat.
There were from what I have found ... 4 Models
Ecconomica - Basic bottom of the range
Tette Apribile - Sunroof model (TA)
Transformabile - Convertable (same spec as TA)
Sport - if you ever find one with a fixed full steel roof you have the holy grail I believe this to be the rarest 500.
All the 500's up till 1960 were Nuova.
here is a mint example of an early car - Ecconomica
http://www.carandclassic.co.uk/car/C346290
here is a TA
http://classicfiat500.co.uk/current...-sale/1959-fiat-500n-in-medium-blue-for-sale/
The ecconomicas were convertable because the soft top was cheaper than the metal roof section on the TA's. The original Ecconomica was so basic most italians refused to buy it as it was so spartan and it was upgraded after a few months. These first models are very rare,.
I have 2 Ecconomicas,1 is a rare RHD the other I am just collecting in Germany that has stood in a barn for 30 years unused and complete although rather rusty.
The sill trim is held on with either wire type clips or replacement nylon/plastic that push into holes in the siills same for the trim along the doors and the rear wings.