Well in VERY short detail I make a copy of the layer and then vertically transform the layer and set it up so the wheels touch.
Then I change the blending layer to soft light (might want to experiment) and then mess with the opacity til it works.
Then I erase the overlap over wheels and buildings and such, and I use the glass filter to distort it. Use a low opacity eraser brush to break the reflection up a little.
After that there's some finishing touches and that's it
