Here is a fun little shot that at first glance looks like it may have been done with layers in Photoshop. I did try it first in Photoshop but cutting out all the individuals was tedious and lacked the proper reflections in the car. What I used was a free download from Microsoft called "Group Shot." This application can be a lifesaver if you have to shoot a group of people and end up with a small "glitch" (people blinking, turning their head, not smiling, etc.) in each shot. Using Group Shot, you can create a composite easily and quickly by selecting those "heads" to be added to the master composite. I used that same approach here by shooting 5 separate images of me washing the car (Sony F707 on a tripod and using the self-timer.) I then selected each position and combined them in a master composite. Give it a try!
I'll be happy to try and answer any questions you may have about the shot or the software.
