In certain parts of Germany (and no doubt other countries) they suffer from marders (which I think it is a marten in Englsh) which love to get into the engine space and nibble anything plastic - cables, pipes etc. This has been a problem for decades, certainly nothing to do with new types of wiring. The usual deterrent is to buy an ultrasonic box which plugs into, and sits on top of, the battery. I worked in Germany for many years on and off, and after suffering marder damage once, bought one of these devices, which certainly seemed to work. I imagine it'd deter all types of rodents.

Heard that the ongoing problem of mice destroying with wiring harnesses could be down to the new eco friendly wiring covers which are particularly attractive to rodents, being made of vegetable products.

The problem apparently is so widespread that manufacturers are refusing warranty claims as the owner is perceived as negligent in not dealing with the infestation.

Not sure that mice are that fussy - they use tried to eat the fake (plastic) buttons on the top of my old 90s Micra's battery and the nylon (or other man-made equivalent) bottom pocket of an old golf bag of mine some years ago (somehoe I doubt if they were that interested in nicking my golf balls, tees and pencil/scorecard book).