I can't say that I understand the purpose of that crate! Myself I think its kinda hard to obtain a car crate, and mostly contain items that I easily could loots. But, cars hasn't always being easy to loot. I remember in December 2016, I've used to find 1-2 car in specific locations around the map. So by that time I could have understand why the crate was lending only 3. I guess, cars was not meant to be common at start, but after the second map update; the too big map with big travel time. I guess by that time, cars have moved from car crates only, to included as rare loots.
Now its almost uncommon if you can't find 4-6 cars when making a fast run around a single location. So I have two opposed opinion on the question.
A) Cars are parts of what made HAVOC being different, unique and pleasant. So about me, they should be available to anyone.
B) Cars are too common and some of his component are disabled.
B1) Cars doesn't require gas, even if the server already have a texture for a gas tank.
B2) The server also have a texture for a key system, but that one, I don't think we need it.
B3) The possibility to rebuild / complete a car shell with looted Battery, motor, and tires is relatively new (March / April)
So about me, there is a few options listed bellow who have to be taken in consideration as either being updated, or upkeep. For the rest, I strongly recommend to keep the car's crate exactly as he is, until staff / owner have time to review how it work. After all, its more a server investment purchase, than a bonus crate for the game.
