Volkswagen is one of the better car companies for NOT using soybased hoses and wire coverings--Toyota and BMW really used them. Anyway, I've found that keeping a rat zapper in front of the Passat in the Garage has done wonders for ending engine bay destruction by mice.
https://www.amazon.com/Electronic-H...&qid=1570213700&sprefix=rat+za,aps,407&sr=8-7
https://www.amazon.com/Electronic-H...&qid=1570213700&sprefix=rat+za,aps,407&sr=8-7