Here's a nice, low poly subway car.
Specifically an R62 model from New York City. Includes just the outer shell, no wheels or interior.
Great for games, visualizations, etc.
Super clean mesh, and simple UV's that would be easy to edit, extend, etc.
STL (Stereolithography, filesize: 26.5 KB), MAX (Autodesk 3ds Max, filesize: 892 KB), FBX (Autodesk FBX, filesize: 892 KB)