Please allow me to guess a few times
(and promise not to laugh at me...)
What if a "W" means that the car has been adopted to Winther-climate. That is, fluids and thermostat and so on, have been switched to winther-suitable parts???
About the "1" on your tag: How about one of these two explanasions: Either an assembly worker with too little to do OR a sign that this is the first car built by the night shift??? (It is not very unusual that the assembly workers find unauthorized ways of doing things. Believe me, I have worked on the assembly line myself)