Fortunately, these sets of images are photoshopped. Though as much as I would love to see one of these on the road...
This form of art is called Trompe L'oeil, or "deceive the eye" in French, and has a long history dating back to the late 16th century. As Wikipedia defines the term:
"...an art technique involving extremely realistic imagery in order to create the optical illusion that the depicted objects appear in three dimensions."
Just like in magic, what the eye sees the mind believes. Trompe L'oeil requires a superior understanding of perspectives. Enjoy the images, and check out the source links for more.