Given two cars, same year, make, and model, it might seem obvious that the one with 50,000 miles is valued higher than the one with 200,000 miles. Is mileage alone enough to make a good second-hand car decision? Unfortunately, it’s all too easy to simply assume fewer miles make for a better deal, but it’s not quite so simple. High-mileage cars and low-mileage cars are not necessarily polar opposites.

In general, it’s a good idea to assume the typical driver puts on about 12,000 miles per year, which can be a good guideline for determining the value of a prospective used car. The average ten-year-old car should have around 120,000 miles on the odometer, anything significantly more or less could indicate trouble brewing. Here are a few examples of how mileage alone can be misleading when considering the value of a used car:

For example, a two-year-old single-owner commuter might have 50,000 miles on it, most of it highway miles. These cars, as well as those of real estate agents and travelling sales representatives, are usually well-maintained and kept in good repair. No one should pass up a used car like this, especially if there are good records of regular maintenance.
Rental cars, though, can usually be had for less money, but with plenty of mileage. For better, rental cars are typically well-maintained and are generally newer model years. Buying a prior rental car that has been properly reconditioned may yield the best value one can find on a used car market. By the way, if you are on the market for a used car, learn more about prior rental cars as used cars.
On the other hand, a ten-year-old sedan, after four owners and 90,000 miles, might be ready for scrap. Some people just don’t care about their cars, satisfied they got their use out of it but wondering why it costs so much to repair it when things break. You’d be hard-pressed to find maintenance records for a car like this, a clear sign you should steer clear.
Further, still, there’s the single-owner ten-year-old “granny” car, the same year, make, and model as the others, but with just 30,000 miles on the odometer, just 3,000 miles per year. Cars like these are usually garaged, meticulously cleaned and maintained, and probably look like they just rolled out of a showroom. Because of the age, things like dry-rot, dried-out oil seals, and weakened battery become a real threat to the longevity of this car, but those can be easily addressed and repaired.
Keeping all this in mind, it can still be difficult to judge between similar vehicles with differing odometer readings. How many miles are too many? Really, it depends on a lot of factors but, if in doubt, shoot for the 12,000-mile/year average. Even so, don’t be afraid of cars that are outside of this range, provided the used car in question has been well maintained and there are records to show that.

Source.. https://www.goautocity.com/used-cars-mileage/

so true @op! most people simply write off a high mileage car

Nobody knows the troubles have seen