When I was taking a database class in college the professor ran through an exercise to help us understand how to organize data within databases. The question he asked the class was: "What makes any car, truck, SUV, etc. unique?" Answers ranged from color to make to manufacturer to trim package; all of those answers were, of course, wrong. Someone in the class finally said something to the effect of the car's serial number being the uniquely identifying feature; the car's serial number, of course, is the VIN.
I, being sort of a smart-ass, commented that the VIN was the uniquely identifying feature only if the VINs were never repeated. The professor agreed and added on that counterfeit VINs would also screw up the process.
Because of this experience with VINs, I was intrigued to read this post on Autoblog that states that car manufacturers are running out of VINs. The suggested solutions seem to be taking VINs from countries that don't produce lots of vehicles and/or reclaim VINs assigned to manufacturers that are no longer in business.
Can you see the people that created the VIN system saying to themselves: "We'll make the VIN number 17 characters long, there's no way we'll ever run out of VINs."?