It's gotta be a photoshop. It's 2 pictures. The first one was taken with the car in the place where the "trailer" is, and the second the car was pulled forward. That way the shadows, reflections, etc are all in the correct place. The pictures were layered. the front of the "trailer" was cut off, and they just photoshopped in the hitch and connecting bar. Not that hard, really.
Also, logistically it doesn't make sense, think of the tongue weight that would put on the car! The wheels on the trailer are SO far back, there's no way the car would be sitting so level to the ground, the ass would be dragging the ground.