Sometimes, you store a bunch of things in your vehicles, and it gets quite messy. Maybe you've got a fuel drum, spare set of clothes, a shroud, maybe a bunch of other crap that you've got stored inside. It might not make sense to store a bunch of stuff inside where you sit.
Perhaps add the ability for outside storage, you get out of your vehicle, you unlock it, and you 'Open Trunk/Boot' Whatever version is coded to use. Different vehicles might have different sizes, such as a mono not being able to hold- really anything. And a Hayasa being able to hold a bunch of stuff. People could easily run along and steal something or jump in the vehicle you've got currently unlocked. But adds a bunch of storage. Perhaps also can be broken in to.