The original design was so nice, but I just could not print it as such in one color. I splitted it, and redesign most of the pieces to make it easily printable. I also added a system to allow the car to actually roll !
The small model is full size, the big one is scaled 200% - see instructions for more details.
The first letter of each stl is the color: R for red, Y for yellow, BK for black, B for blue, W for white and G for Grey. I also printed the police light in a transparent blue to have a more real effect.
Print one of each stl and that's it !