GTA V Vehicle Storage
I found this on a GameFAQs thread.
The original post is a bit long winded, so here is a summary:
Land Vehicles
They're simply stored in your garages as you expect, regardless of whether you stole them or bought them. If you take one out and crashes it, you'll have to get another.
Other Vehicles (helipads, hangars, and boat docks)
You can store stolen vehicles as per land vehicle. However, purchased vehicles can be spawned infinitely, but they immediately replace the existing vehicle inside the storage compartment.
e.g.) If you stored a stolen jet in a hanger, but decide to summon one of your purchased planes, your jet gets replaced instantly.