So either these rodents have to die or I need to find a way to keep them away from my cars. Does anyone have a good pest repellent that actually works? I have heard of the ultrasonic kind that makes noise they don't like, but I have never heard from anyone that has actually had experience with that. I'm sure I am not the first one to have this problem.
I have been driving my old Grand Prix for the past week, since I finally got the water pump on it and everything is all working at the same time. So my Bonneville just sat there. I have to park all my cars outside, and the area in which I live is somewhat rural. I have noticed since I have lived here that the plug wires on my Lemans have been getting nibbled. It hasn't been a problem because they aren't chewed through. It is like whatever is nibbling on them doesn't like the taste and gives up after a couple of bites.
So tonight I got a wild hair and decided to drive my Bonneville after it had sat for over a week. It started up immediately like it is supposed to, but I noticed it was missing. As in the engine was not firing correctly missing. When I looked under the hood, one of my plug wires had been chewed apart. So either the chewing varmint has grown up, or these Bonnevile wires are a lot tastier than the high-dollar Taylor wires on my Lemans.
Luckily I had a spare plug wire. For what it'* worth, my 1990 Bonneville takes the same style of plug ends as the old Pontiac V8 HEI plug wires. I put it on and was on my way, but not before clearing out a nest of leaves and fluff the little rodents stacked on top of my engine. Apart from the obvious plug wire issue, the nest material appears to be a possible fire hazard.

Someone was telling me about using bounce dryer sheets. I guess mice don't like the smell.

I'm not sure where I could place those in the engine compartment so they wouldn't be as much of a problem as the nest material. But I like the idea of the low tech approach.

Not usre if it is a feasible option for ou, but if you live ina rural area, why not go ultra-low tech and get an outdoor cat or two. Put out some food and water once and a while and there you go. You just have to make sure the cats aren't up in the engine bay. I have heard horror stories.
Anyway, good luck with this. That would certianly drive me nuts.

I've heard that good old fashoned moth balls keep varmints away. I know the smell would keep me away!!

I've got the same freakin' problem! I've caught/killed 6 mice in my car the past year. One of them met an interesting death in my HVAC fan. Anyways, sseimatt93 was sayin he uses some kind of soap during the winter to keep them out of his.

Yes, mothballs seem to work. Just a couple, three in a small onion bag tied near the rear firewall (way away from your fresh air vent). You will smell them a little inside (the mothballs), but I haven't had trouble with mice or chipmunks since.

SSEimatt93 used Irish Springs Original Bar soap this winter to ward off the mice, worked WELL.

There are cats here already. They are useless. Or it could be that they can't fit in the spaces under the hood where the rodents are nesting.
Since Irish Spring is slightly less offensive smelling than mothballs, I will give that a try. I had a box of mothballs in my Lemans for a while in case I couldn't find high octane fuel for it. I never opened the box but they still stunk so bad I took them out. I bet they would work on rodents, because they would sure work on me. I'll keep that in mind as a last resort.

Irish Spring sounds like a good plan to me.
Weird about the cats. Must not have been around when the mice came out.