You can take a whole home theater system:
https://i.imgur.com/kJDOBA8.jpg
2x floorstanding speakers
center speaker
subwoofer
receiver
power filter (not pictured)
cables/controllers/HTPC boxes
and still have the front passenger seat free ;D ;D
hahhahahaa yeah even the sedan can swallow up heaps, I picked up a single bed in mine! with the rear seats down you have over 2m or nearly 7feet of space, the avants are of course better…I know they never made it to the US - here (new Zealand) they are about 5k more than a sedan
So much more room for activities!