It can be a strong option for drivers who cover many kilometers, especially on longer trips. The key is to compare maintenance history, mileage, engine condition and past usage.
There is no single number. A well-maintained diesel with higher mileage can still be a better buy than a lower-mileage car with poor service history.
Often yes, because they are commonly chosen for regular long trips. Even so, it is worth checking service history, clutch, turbo and overall condition before buying.
Check cold starts, smoke, unusual noises, maintenance history, fuel injection system and wear on components that are sensitive to high mileage.