I agree that Chassis Number is the preferred ID but as long as the DMV is involved (as well as insurance, mechanical invoices, etc), we gotta live with it as the VIN as well.
Here's another example of VIN confusion: on my car, the paint codes & build number plate are on the driver's A-piller door jamb. On more than one occasion, people looking for the VIN, open the door and use that number. Funny thing is it's darn close! Chassis 000871, Build number 00881. I think I even have an old DMV registration with these mixed up.
James
63 230SL