Put down the back bench in 323 to get more space than 356 liters. It’s important that trunk arrangement of Mazda is efficient. You may always put small shopping things in 323 trunk. The figure was formed by Mazda during designing the 2001 year models. It’s possible to arrange 356 liters of things in Mazda 323 cargo space.
The number of 356 liters cargo space is provided by Mazda and is appropriate for vehicle. But don’t forget about weight rules of 2002 Mazda. It’s easy to overload Mazda 323 but try to avoid this.