Open Steering Shaft

In every vehicle I have ever seen in the price range of a Prius, it is "exposed" if you twist yourself down below and look up.

A squirrel shouldn't be able to get in the cabin unless you left a window/door open.

 

And if they're getting in, there could be more problems, chewed wires for example.

 

you might be able to fashion some type of squirrel guard with hardware cloth or the like.

 

Finding nuts inside is common when you get field mice living in the car. Open up your cabin air filter and you'll most likely find a nest or at least a hoard of old acorns and things.

There is more than one animal that eats acorns... Having a squirrel inside a car is not really possible unless it is really exposed by user error. Having mice inside a car happens all the time as they only need a tiny fraction of an inch opening (of which there are many) to gain access to the cabin, chew on wires, pee on upholstery, etc. If you haven't seen this "squirrel" yet, I would assume it is field mice. This time of the year, they are seeking out warmer areas before the cold hits. Houses and vehicles are being inundated with the little buggers.

Don't poison them, you'll kill them and all the other food chain. But a couple bags of strongly smelling herbs is usually enough to drive them away.

 

search here for mice threads, there are some great write ups with pics on how to cover all the entry points. it's not a task for the feint of heart. i'm a poison guy myself, they carry too many diseases to fool around with. all the best!

 

You just buy the herb bags already mixed from Amazon and they work great. Punch a few holes in them when they come, and done.

Your problem is that they've been in there before and your car smells like it. You can't just put some herbs in there and make them go away. First you have to get rid of the problem. The herbs prevent the problem, you're past that stage. You need a really good interior detail to get up all the feces and urine that is no doubt throughout the car at this point. Then you can add the herbs.

 

Not a lot of suggestions, would think screens on the engine air intake, cabin air intake (if needed, not sure, the cabin air exit flaps (under hatch floor, both sides). First and foremost: get them gone asap, they could be causing irreparable damage, chewing wiring harness for example.

Our Shiba Inu chased off the one intruder we had.

 

That makes much more sense.

Recirculating the air puts a flap down which blocks the vent tube a bit. But there are lots of openings. Mice don't need much of a gap to get through.

You don't keep mice out of the hood without making full enclosed boxes. There are way too many openings around the car and engine for them to get in.

 

I think the most likely egress is the cabin air intake, but not sure. Again, there's two air exit flaps, under the rear hatch floor, in the sub-floor walls, either side. There's flaps over them, so putting in a grill would be tricky. Probably trick for mice too, suspect it's the (pictured) air intake they're using. This is a screen grab from your link, screen on the cabin air intake:



See also @NutzAboutBolts video on spark plug change here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

There's a good step-by-step about removing the cowl.

All of this is for 3rd gen, not the v, but hopefully similar enough.