[Germaniac]

Just had a similar discussion with EdT, and this is what I had mentioned:

You will have to deal with moisture one way or the other, since "breathable" is a term which is leaving lots of space for definition as I have experienced with "breathable" covers for our bikes.
Place one or two dehumidifiers (the kind you can dry in a microwave, on a radiator etc.) in your car and check them regulary. Another tip is to place a number of those floating noodles under the cover - they improve the climate by allowing more air circulating, and the space might even save the metal being dented by smaller hail stones, chestnuts etc.

With a good cover with an inner microfleece (or similar) layer, the risk of chafing the paint should be small. If you have the space, you might want to consider of getting a portable shelter or tent. Wash the car and let it dry before putting on the cover. If possible, apply some car wax. Apply some silicone or deer tallow to the door seals. Squeeze a bit of antifreeze into the key slots of the doors.
Vacuum the engine bay, remove all the leaves, twigs and other debris.

I wouldn't go through the ordeal of draining the washer fluid but making sure it's at least not freezing at -15 - -20C° (which is also recommended for the daily use in the cold season - think of the wind chill).

Apply at least 0.5 bar more pressure than recommended to the tires. If you want, get those thingies (don't know how they are called in English):

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Take out the battery and store it in a frostfree place. If this is not possible, I recommend to buy a battery pulser/refresher/jogger and/or a charger which has a trickle charge mode. To avoid losing the settings, a memory save might work:

General PDP Template

www.canadiantire.ca

 

[Germaniac]

Mice can be an issue but these cars are decently sealed so mice shouldn't be able to get inside. I park my cars outside beside my house, and have not had mouse issues there. But the mousetraps in the house gets a mouse a week or so! I guess I shouldn't curse the neghbourhood feral (?) cat for sitting on the convertible roof. It sheds fur on the top, but maybe it also keeps the mice away.

I would be more afraid of martens, but luckily, it seems that the cars of our neighbours are more tasty to them. 😁

I leave my NG9-3 unlocked under the car cover, and the battery installed. I think this prevents excessive drain on the battery, which I charge up every couple of weeks. When I took the battery out for winter, when I reinstalled I had a lot of steering column lock failures and key not accepted. There was no permanent issue (and I have access to a Tech II), however the plan of just leaving the car and charging periodically seems to work fine.

Apart from the usual drain, very low temperatures are contributing to wear out batteries. Good for you if you have the opportunity to charge it regulary - those who can't may want to take them out though (you should see our landlady getting on the brink of a meltdown whenever she notices someone using the outlet in the garden although it's us tenants paying for the electricity used...).

I don't understand Saab's recommendations about washer fluid. Put in some good -40º fluid, run the front and rear washers, including headlight, until you are sure the good stuff has pushed out any old summer fluid. It will be fine sitting like that.

When it's really cold, it doesn't matter anyway as the lines and nozzles will freeze.

Another general tip: don't use the parking brake unless you really have to. If possible, apply some grease or fluid lubricant to the open cables, links etc.

 

[Germaniac]

I suppose, but does it really matter, 2 days vs 2 weeks or 2 months?

Depends on the outside temperatures and the nozzles themselves...I had cars which lines and nozzles didn't froze for days even with nighttime temperatures of -10°C, and I had cars which refused to wash the windshield after a night with slight frost.

I think that Saab was afraid that owners (especially in the US) might forget to fill up the washer tank with antifreeze, somehow something gets broken and then it goes all down south in front of a judge.
It's like with the warning "don't put small animals in the microwave to dry them".

 

[Germaniac]

I found that mothballs just make the car smell more like mothballs, masking the smell of the mice that happily lived in the car beside the mothballs.

You can avoid that by keeping a cat inside the car. Minor disadvantage: after a while, the interior smells like a litter box.

On a serious note, most rodents and also weasles, martens etc. don't care much about smells as long as they don't signal an actual danger or competitor. Sometimes special repellents work, sometimes not.