Does anyone remember/know where I can find an episode of Car Talk that featured a letter from a guy who had wired his car to deliver a jolt of current to the critters that were inhabiting his engine compartment? An Electrocution-On-Demand kind of set-up.
I think you may be referring to a jolt type fence installed around the cars perimeter. They are available at any big box outlet. We tried one for our dog but I had more zaps than the dog did. Dryer sheets and Irish spring soap are rumored to be good inhibitors to rodents. I had to help a friend rewire a car due to a groundhog gnawing through the main wiring harness so I can understand your trouble. This summer I had to cut 3 inches off the nozzle from a gas can because some critter chewed it to shreds, amazing what they eat when they get hungry!
No, this was a home-made creation that made the whole frame of the car hot. He had to remember to disconnect it before attempting to touch the car and, if memory serves, he got a couple of bold surprises himself. I will take a look at the perimeter fence you mention, but fear that I’ll be getting zapped like you. Gotta consider how much smaller rats are than dogs, too… Okay, your friend’s groundhog story is a first for me! Gnawing sons-of-guns. This is war!