It’s possible to arrange 182 liters of things in Fiat 500 cargo space. You can usually get more than 185 liters by putting down back seat in 500. The shape of Fiat’s trunk is quite appropriate. You may always put small shopping things in 500 trunk. The figure was formed by Fiat during designing the 2013 year models.
Fiat proves it to be wise decision of making cargo capacity at 185 liters. Check also if your luggage in 2013 Fiat isn’t heavier than needed. Otherwise you can cause great problems for Fiat 500 by loading it.