I am actually more curious about the cost per mile for the next person, who buys the car with 200,000 miles on it, and drives the remaining 20,000-60,000 miles of its life. I see lots of cars for sale with high miles like that, and there are people who buy them. I usually try to avoid cars with more than 130,000 miles, but I decided to buy a truck with 209,000 miles on it not too long ago. I figured the price was right, and I only plan to put about 6,000 miles per year on this truck, so it could last a long time.
It really cannot be legitimately determined. It could be great for 50,000 miles with only minimal work or you could end up with major repairs in a couple months. The condition of a new car can be determined, but the condition of a well used car can be all over the board. So you just take your chance. Odds are improved with the particular brand and model, they way it was used and cared for and so on, but there is no one size fits all.