How often do you think about the stuff you put in your car's trunk? Probably not that often, but you should: If it's not secured properly, your luggage can easily become a deadly projectile in a crash.
This video from Switzerland's shows how the luggage in a hatchback, wagon or SUV gets thrown around in a head-on collision. All the airbags and seat belts in the world won't help you if you get a suitcase to the head.
It also doesn't matter that the Volkswagen Passat wagon in this video is old. Physics still apply, even in the safest cars of 2016. –leave a few in your lift-back's trunk. It's cheap insurance against a bad crash from being more painful.