For this, it really depends on what style you are analyzing. If you are talking about canned or bottled versions, you can leave them in your car. With that said, it is not wise to do so in the warmer months as the liquid may be flammable. During colder months, though, they should be fine resting in your trunk. As for washer fluids, it is not really necessary to do so. If your reservoir is filled with the liquid, it will last quite a while (depending on use) and you can probably get away with leaving the actual jug in your garage or home.