Having worked 26 years at a Chrysler assembly plant, I can verify that employees would follow their ordered car down the line and add some "extras". It was common when I was installing wheels and tires for employees to ask for a better tire/rim combo. That was in the 80's and 90's. Now cars are audited when they roll off the line, and then again checked by a seperate quality/security company before going to the shipping yard.
True story. When we first started making Intrepids a emplyee ordered a base model, followed it down the line, getting all the power options added on. The problem was he never thought to have the proper wiring harnesses installed. When the car reached the end of the final line, the operator doing the electrical test flagged the car as none of the power options worked. Long story short, car was audited, guy got fired, and rehired 6 months later.
I also remember a guy who worked at GM, and did the same thing. Ordered a base car with few options, then had it fully loaded going down the line. The car made it down the line and to the dealership. Problem was the salesman at the dealership realized that base car was now fully loaded, and the dealership was only charged for the base model. The dealership sold the car at a price that reflected the options on the car, and reordered the employees base model.