The narrator of this video, Tim at Cape Night Photography, gives little away as to why these bits of NYC mass transit ended up in a desert, explaining during his walk-through: "There are three old New York City subway cars... in the middle of the desert, really surreal. Interestingly enough, they've been cut in half." There are also a bunch of New York City buses, and an old "shot up taxi cab" that may or may not be authentic. We've contacted Tim (and the MTA) to find out more about these relics and where they reside, and will update when we hear back. Until then, enjoy!:
UPDATE: A spokesman for the MTA tells us, "The subway cars appear to be old R30s from the BMT lines, done up to look like newer models. We think the bus may not be real, however—tough to tell."
UPDATE II: Tim tells us the subway cars were in a junkyard in California, but cannot give the exact location due to a nondisclosure agreement. Though he did tell us that he "heard that they are used sometimes television and movie production."