Going on a road trip with family means that you have to deal with a lot of luggage. But if you can't fit it all in the trunk of the car, you may find that you have to just shove bags underneath the back seats instead. This takes up all-important space, makes the car feel messy, and is generally just overwhelming. You can solve that problem by using carabiners or hooks, though.
By placing these carabiners on the headrest of the front seats, you can then hook the bags onto them and tidy up the car. It also means that they're easy to reach if you need them.