We already make car wiring insulation out of soya-based plastic, which is highly biodegradable and palatable to micro- and macro-organisms of all sorts.
Which is why so many modern cars have weird electrical faults and fires.
I can attest that the soya-based wiring can be a nightmare in some locales. A family member bought a new Acura in the 2010s and the car was a constant target of the local rat population that would climb into the engine bay and fill up on wiring insulation like it was gummy candy. He had the wiring harnesses replaced several times but ultimately gave up and sold it after the final repair.
It seems like they could incorporate capsaicin and other deterrents into the polymers, but that probably isn't pleasant for individuals involved in the production process.
I can attest that the soya-based wiring can be a nightmare in some locales. A family member bought a new Acura in the 2010s and the car was a constant target of the local rat population that would climb into the engine bay and fill up on wiring insulation like it was gummy candy. He had the wiring harnesses replaced several times but ultimately gave up and sold it after the final repair.
It seems like they could incorporate capsaicin and other deterrents into the polymers, but that probably isn't pleasant for individuals involved in the production process.