What real protection does parking car in a garage do?

I’m not referring to theft.

I bought a new car and kept it in the garage when not in use for 10 years. Then after moving we used the space in the garage for other things so for the next 10 years I kept the car outside. After 20 years of ownership I donated the car and bought another one.

I don’t recall any noticeable progressive deterioration to the outside of the car in the last 10 years it was parked outside instead of in the garage. Most employers have uncovered parking so the car is outside for 8-9 hours, 5 days a week anyway.

So what sort of protection from the environment is really a concern with having a car outside all the time instead of in a garage?

Depends on where you live, what the weather/sunlight is like, whether they salt roads, what kinds of trees are nearby… Live someplace where it hails a lot, for example, and see if your “outdoor” car matches the control for very long.

Don’t have to scrape ice and/or snow off the car in the morning.

They aren’t sand-blasted with alkali grit and the foam in the seats aren’t reduced to powder by the sun.

No bird crap or tree sperm. That’s a plus.

Bird shit, hail, falling trees/branches, rodent damage.

I’ve never in my adult life had the use of a garage at home. But my cars seem to last just fine. Sold my 2000 Honda Accord last summer, 16.5 years after buying it. The exterior was still in decent shape, other than a dent (unrelated to weather, of course) - some fading of the paint, but still dark blue after all these years, and the interior fabric was a little bit faded as well, but the fabric and cushions were still in good shape.

(If it had still been in good shape mechanically, I’d have kept it, but after >230K miles, several issues were cropping up at the same time.)

I obviously don’t know how it would have lasted if we’d had a garage, but if the body and interior easily outlast the car’s mechanical workings despite being outside for that many years, it’s hard to see how the absence of a garage is a problem.

Don’t forget cats spraying on them.

Homeowners started building garages during the couple of decades when all cars were open, and everything from weather to raccoons could get in. In fact, the garages wee already there, for parking their pre-motorized carriages. When cars became more weatherproof, lots of people already had garages, so just kept up the tradition.

A garage, or carport, does keep precipitation and sunlight off, which are relevant factors in some environments. Particularly dew and ice, which are not easy to remove in the morning.

Sure, there’s that, too, but I was listing things that could actually damage the vehicle. Whether the damage is minor or unlikely, it still combines with factors such as convenience and safety to make a convincing argument to having a garage. Of course, the tree could just as easily smash your garage filled with junk and miss the car in the driveway!

Depends on the climate where you live, but parking your car in the garage rather than exposing it to the extremes of summer/winter will extend the life of your tires and other rubber parts.

Garages keep direct sunlight off the paint, this makes a big difference over time. UV damage of plastic and vinyl, and the big one, tires. Tires don’t last as long as we’d like, even with good tread they will eventually become unsafe due to exposure to ozone, oxygen etc. But keeping them out of direct sunlight helps noticeably prolong their life.

Even an unheated garage makes starting the engine a lot less hassle on a daily driver as at least some of the latent heat of the previous day will be retained. It’s a LOT nicer on a cold winter morning. Then there’s the beauty of not having to scrape ice and snow off, bird shit, pollen, sticky insect goo and the rest of it - like tree branches falling on the car, or leaves and debris filling the heater box. Maintenance can be done with a lot less hassle.

Parking on the street means a lot more chance of getting damaged or even totaled. Insurance premiums reflect that. A car or truck needs a garage, if at all possible.

Exactly why I insisted that when we moved here, I would be parking in the garage. I can load and unload the car regardless of weather. And even in the coldest weather, I don’t think the temp in the garage ever got below 40°, so no trouble starting it on cold mornings.

In our case it’s pretty different than OP’s assumptions: northeast US with snow storms and salt on the roads, parking outside means parallel parking on urban street, and we don’t commute so the garaged car is only outside in store parking lots, overnight trips, visits to friends or when actually driving it, much less than 8-9 hrs/day on average. And we generally have two cars the ‘nice’ one of which is garaged and doesn’t usually get driven when there’s snow on the ground.

In this special set of circumstances it makes a big difference for the ‘nice’ car. We had a Lexus garaged for 8 yrs and it looked like a million bucks; we moved it on street when the garage was torn down for a new development, noticeable deterioration in 2 yrs till we sold it. Now our ‘street car’ is our son’s 8 yr old Honda he doesn’t use much, we move it around to avoid street cleaning tickets and use in return for local trips. It’s always been on street and it’s all dinged up*, looks like crap for its age. The ‘nice’ car is a BMW which looks brand new after 2.5 yrs, in a new garage building and seldom driven when there’s snow. Unlike previous garage this one stays warm inside, car is also never started below around 60 deg F.

*very narrow streets and drunks do stuff like break off the mirrors. Not a lot of deliberate (sober) vandalism in recent years, that used to also happen more often to our street cars years ago.

I personally consider eliminating exposure to rain, snow, cold, heat, UV, photons (i.e. the sun) and streetside incidents real protection. I’ve owned three vehicles in my life. All of them garaged. All of them were mechanically sound and in fair cosmetic condition for as long as I owned them. My longest duration car was 35 years; the shortest: 18. I am convinced keeping my vehicles garaged extended their lives dramatically.

I live someplace where the car dealerships occasionally have hail sales to sell off cars with minor damage from hailstorms. Dents in the body, dinged windshields and the like. A garage prevents that sort of damage. I went 1 winter here without a garage and the most consistent advantage to having one is not having the scrape ice and snow off the car in the winter.

Avoiding hail and vandalism are my two biggest concerns.

Where do you live? This is obviously going be be highly dependent on your local weather.

Wishing they had garages.

Out here, the sun will destroy a clear coat in 5-10 years. My 2002 Hyundai Santa Fe looked sad (to coin a phrase) after being outside for most of it’s life. The clear coat was oxidized down to the paint - but only on the southern-facing side of the car. It looked a bit like this, but way worse.