Following is cut-n-paste from "tracking thread."
"While the VIN is actually placed onto the car as it goes down the production line, it assigned before then, so that the parts collected from all the off-site suppliers have a reference to tie to. This allows all the parts, and all the options to be properly allocated/collected and assigned to the specific eventual VIN destination (your car).
It is a similar process to all complex manufacturing. Say you order a computer on line, specifying advanced capacity hard drive, an extra large monitor, etc. The parts are "warehouse location" identified, located and assigned to a special serial number that will become your unique computer. The two differences are that all computer parts are normally in one mega-warehouse, whereas the Corvette's parts are coming from all the off-location suppliers. Secondly, your computer has a serial number, whereas you car has a vehicle identification number (VIN). At a certain point, all your Corvette's parts are shipped so that they arrive at the Bowling Green Assembly Plant a day or sometimes hours before your car's chassis starts its journey down the line. At this point the master VIN machine (yes a machine comes down onto the car from above and affixes its dashboard VIN), affixes your actual VIN to your car, then in the next roughly 15 hours, the rest of your car's options and parts get added to your car. Your baby is born."