Stone Marten (Martes foina)
Marten's are omnivores, their diet includes worms, eggs, fruit, other smaller mammals and high-tension leads in car engines.
As in the case of Renate's little Renault Clio the Marten completely ate through the lead for the number 1 cylinder. Probably a mid-night snack after finding a nice warm spot to sleep for the day.
This guy must have had good taste as he picked the most extensive cable at 70 euro.