Hi Ed,
To my knowledge, MWG stands for Magyar Wagon és Gépgyar (MWG). This plant was created for producing railway engines and carriages. Information in english over this producer can be found in Dénes Bernad and Charles Kliment's books "Magyar Warriors: The History of the Royal Hungarian Armed Forces, 1919-1945" here:
https://books.google.ch/books?id=TP4...20Györ&f=false
So Manfred Weiss was a different producer but which pooled up with MWG and others for the war effort.
Cheers
Marc