there's 3 or 4 at the local drag strip; guys "rent" them to park their hotrods in them during the offseason or between races. But I can tell you this, once a car is inside, there is zero room to get into/out of the car, and certainly no room to work on it. My friend's Chevelle is kept in one.
Years ago one of my friends found/bought some property in the hills, alongside the river (creek). There was no shelter of any kind, so he bought a couple old connex's, set them side by side, and buried them in the side of the hill. Once buried into the hill, they cut out a couple doorways inside to "connect" them. They were really nice! I spent many a night in "them", you know, take the girlfriend(s), or a lot of times just by myself to get away from the dang city. Take .22 rifle and a fishing pole; stay a week, eat off the land. Hard way to live but it was a nice break. The connex's were STOUT. They stack those things 3, 4 high on the docks and in the yards, so if they can handle that kind of weight on top of them they'll be fine--and those two in the hillside are STILL there; gosh, has to be going on 15 years now.