This is the original figure before my customizing. (Image from www.seibertron.com)
Robot mode of Sergeant Kup from Hasbro's Transformers Generations line. 6 inch figure. I've been going back, customizing and adding details to many different Transformers figures to make them more life-like. For this figure, I've added all the rust, mud splatter, and grime. I also painted in the silver hubcaps (previously unpainted black plastic), the silver grated stomach plate (previously unpainted green plastic), and the red tail lights (previously unpainted clear plastic). 
Vehicle mode
This is the original vehicle before customizing. (Image from www.seibertron.com)
Original vehicle without painted grey striping along the bottom of the sides. (Image from www.seibertron.com)
Original vehicle without the grey strip along the back or grey exhaust pipes. (Image from www.seibertron.com)
All rust discoloration and mud splatter added by myself. This includes the simulated mud splatter behind the wheels. Also, the gray coloring on the bottom of the side door sections was added by myself. It seemed odd to me to have grey on the front and back but only green on the sides.
Underside of the Vehicle mode where some robot sections are visible. Here, you can see the simulated mud in the crevasses of the wheels. This was accomplished by using the paint-wipe technique.
Window wipers painted black (previously unpainted clear plastic).
The back door indeed folds down. Here you can see the added dried mud detail on the interior of the back of the truck. The floor of the storage area is also the bottom of the robot's feet, so I figured this area should be fairly dirty.
