Subaru 2004 Impreza Owner's Manual page 267

Interior equipment
maximum load capacity is 44 lbs (20 kg) per an
hook.
6-18
Under-floor storage compartment (if
equipped)
The storage compartment is located under the floor of
the cargo area and can be used to store small items.
To open the lid, pull the tab up.
Hang the hook provided on the under side of the lid on
the rear edge of the roof to keep the lid open.
NOTE
When storing a flat tire, put the storage tray in the
cargo area.