A 17-year-old car with 100,000 miles on it? Your daughter is brave and the essence of frugality and practicality. And I mean that in the most positive sense!
I, on the other hand, won’t keep a car for more than 3 years, and I lease. I view cars like a pencil: very useful, but a declining asset like a pencil.
On used car prices, about a year and a half ago (late 2019 before the pandemic), we got an estimate of $20,000 for my wife’s relatively new car. Today, 1.5 years and about 12,000 miles later, we got an offer for $24,000, $4000 more than a while back. We’re tempted to take it, but only if we can get a new car at a good deal. We’re still sorting that out. But, at least from my personal experience, used car prices for relatively new vehicles (and with or without extremely high mileage) has gone through the roof.
One other reason that I lease a car for three years: we’re big on EVs or PHEVs (plug-in hybrid EVs). The technology is changing so fast for these cars that I don’t want to be saddled with something that has a range of 100 miles when the new cars are getting much more than that (as an example).
Also, in California, for EVs and PHEVs, we get a sticker that allows us to use carpool/HOV lanes and cross bridges for a reduced toll during rush hour. In the Bay Area, with the huge traffic and limited lane freeways, having this sticker can save tons of time. So, I look at the cars that qualify for the sticker, and it is AMAZING how many more cars today qualify for the sticker than just 2 years ago. All the manufacturers seem to be moving to phase out gas-only vehicles.
In any event, your daughter will go far! Hopefully, at least 100,000 more miles in the literal sense! 