The steel monocoque frame provides greater rigidity–delivering a superior ride and long-term durability. The steel body will last for generations and not deteriorate quickly like plastic. It’s one of the reasons why you see so many vintage Vespas from the ’50’s and ’60’s on the road today.
Compared to other inexpensive scooters, it is more expensive to build the Vespa monocoque steel frame. The advantages of monocoque construction include solidity and heft, which translates to a smooth, stable ride, among other things. The minuses include higher cost and greater weight.
VESPARK: Piaggio Vespa 3S Showpark / Dealer at Medan North Sumatra Indonesia