I'm confused. If it runs great, then why are you paying $450 to have it inspected and either way, that seems like a very high price for an inspection. Normally that's about an hour booked at $150 per, so...
Low MPG isn't much of a downside if you don't put on many miles per year. The carbon footprint would be higher to make (and drive) a new car to replace it at that rate, and certainly the cost in vehicle depreciation alone.
However, if sightseeing means taking it on long trips, that is one thing I don't like to do with vehicles past a certain age, would sooner rent something or even buy something newer, use it a while, then resell it at nearly what you paid. This post-covid market might be one snag in that plan, since it wouldn't be surprising if used vehicle prices continue to drop a bit, especially with the flood of overpriced new vehicles falling in value just sitting new on dealer lots, which could mean a double hit in depreciation compared to doing something like that a half dozen years ago.
I wouldn't worry too much about the rubber hoses that Bonzai mentioned, I mean that if they are a concern then I'd just replace them, but it's also things like internal seals that will shrinkf if fluid isn't circulated around, greased components losing some oil separation out of the grease, flat spots on tires, rusted brake rotors or rodent damage (if stored outdoors), and if your low mileage is due to mostly short trips, letting the (used) oil sit for long periods can increase sludge buildup.
I haven't had anyone look at the car for several years other than a 20 minute smog-only test station workup for the California Motor Vehicle Department every 2 years. Had one done a couple months ago. Last time anybody inspected otherwise was June 21, 2014, so, ten years ago. I had a highly recommended auto repair shop fix the AC. I was pleased and a week later, that June date I mention, I had them do the 30,000 mile service, well, that's what I asked them to do. The mileage was actually 27,415 (the owner's manual says to do it after 30k or 24 months, so I figured I was actually overdue, it had been way longer than 24 months since any previous comprehensive service/inspection).
So, I figure I should bring it to somebody, certainly before I think about taking long trips. I figure I can join AAA, that would be some peace of mind. At least I could get free towing, if it comes to that.
$450 struck me as a lot too (I called them, was told that on the phone, I have never been there). I called a highly rated place previously and was told they wouldn't work on my car because it's too old. I could call around and try to find someone cheaper. I only figured I shouldn't worry about the $450 because fixing the dents from the chimney bricks that fell on it would cost literally 10 times as much! They are calling it a "minor inspection," so yeah, seems like a lot. He said they'd change the oil, check fluids, wiper blades, some other stuff I can't remember, this was months ago, but I wrote that specific stuff down. What does a major inspection run with these guys? It is Berkeley and COL is high in the Bay Area. Yelp posters mostly say they find them reasonable, professional, personal. Anyway, 10 years since anyone has even lubed it, greased whatever, inspected rubber is a long time. Nobody's checked the brakes. I guess I checked fluids a few times, besides changing oil and oil filter, which I've done myself in my driveway, every year or two with Mobil Full Synthetic.
Can all that stuff you mention be checked in an hour's inspection?