Some great points about the car. I haven't indicated to anyone in the family other than my wife that I might have a slight interest, so there will be no hurt feelings by saying no.
I suspect the car will be offered around $1,000. Thinking about what it needs, tires are already a big expense. No clue what the frame's condition is, but the body panels already have some rust that seems reasonable/average for its age.
But the kicker I think might just be the maintenance history. The car has been in the extended family since new, starting with one of my sister-in-law's husband's parents. When they stopped driving, they passed their car down to him. I don't know what they were like in terms of maintaining vehicles, but they struck me as diligent people. After it left them, I think is where it went downhill for the vehicles. Another car of theirs passed on to their son had a transmission die. A Hyundai Tucson of similar vintage to the Sonata, and it only had around 100,000 km (62,000 miles). They asked me when the mechanic tried a last ditch effort to save it with a fluid change if that, and the quote for transmission replacement was reasonable. The way they talked about the car made it sound like a tranny fluid change was not something they'd ever think of. The Caravan that they had, then sold to my in-laws also doesn't seem to be in the greatest shape, and makes all sorts of weird noises, and feels like it will die at any moment.
I think the answer is clear after thinking about it. Stay away from the Sonata.