Around here, where growth is infinitesimal, the only new storefronts are for medical offices and huge auto parts stores.
I thought nobody worked on their cars anymore because you can’t do much in a computerized engine.
People must be buying something. What do you get?
I can’t recall ever having bought anything else at such a store.
A lot of people seem to be buying stuff to accessorise or detail their cars. You can still get brakes and other consumables but they can be Temu grade and not always that much cheaper than the dealers. Air fresheners always sell well…
I bought one of those emergency tire inflaters I saw advertised online.
Not everyone has a new or newish car. Plenty of cars still on the road that can be worked on yourself.
…Although I was about to say that until fairly recently I worked on my own cars myself then I did the mental math and it’s been well over 20 years so thanks for making me feel old 
But even these days people buy oil, filters, fluids, batteries etc…
I have bought those three, plus one time I bought a replacement cap for the valve stem on one of my tires.
The last time I was in one was to buy a sunscreen for the front window. That was a few cars ago.
All the answers here are similarly for comparative pocket change. Somebody has to be spending big bucks just to keep the old stores in business, let alone open many more.
Air filters, both for the engine and the cabin. In most cars these are incredibly simple to change.
I think my next purchase is probably going to be a master brake cylinder for an old 1991 Ford Ranger. What is surprising to me though isn’t that I can still buy one, but that it is most likely to be in stock when I do need it.
Me too. I can’t get the size of wiper I need for my rear window at Costco so I go to the auto parts store.
If I get light bulbs for the headlights or turn signals, they install them for me free.
And I’m due for engine filter and cabin filter.
I still buy parts; literally the only reason I will go into an auto parts store.
We went to an auto parts place a couple days ago to get a replacement battery for a key fob.
Assorted fluids, locking gas caps, replacement oil caps, decent wiper blades, equipment and chemicals for detailing…I’m sure I’m forgetting something. I buy bulbs and air filters from RockAuto due to a better selection; that’s also where I get cheap wiper blades (for a Wrangler; if you install modern streamlined wiper blades, they turn into little airfoils due to the angle of the windshield). I’ve also gone to auto parts stores for battery testing.
The dealership-affiliated shop where I take my Jeeps uses O’Reilly for parts when OEM isn’t an option. That’s an interesting choice to me, since they have an Advance Auto Parts within walking distance of the shop.
Brake pads, oil filters.
Just a year and a half I had to replace the battery and alternator for my 2002 Saturn, but mostly oil, brakes and wipers.
We do a lot of DIY car work, and the vast majority comes from RockAuto.
Oil and filters comes from Walmart.
The J.C. Whintey company was sold and the catalog isn’t published anymore, but there’s still an online website, which seems to have more than 38,000 individual parts.
That’s part of my point. Very few of these items mentioned above can’t be found online. They don’t need personal handling. They aren’t emergency equipment that can’t wait a day or two.
Are the stores just fun to visit and walk around in? I know hardware stores are, even I need only one item.
Or are they like Home Depot, which does most of its business catering to professionals who buy loads of stuff?
You can buy tons of car parts in an auto parts store. I’ve been in endless situations where my car or someone elses car had a problem, I diagnosed it and ordered the part for pick up at the auto parts store. Then I had my mechanic swap it out.
The actual store that you walk around in is just part of the store. Theres an entire area of shelves full of actual car parts behind the desk.
Another thing to consider is that the online market is full of inferior chinese car parts that can and will break. If you go to a brick and mortar store and order the parts, they will match OEM specifications.
Probably this. Every parts house I know of (O’Reilly, Advance, Autozone, NAPA) employs one or more delivery drivers to haul parts to the independent garages and sometimes the dealerships.