The mileage of the car defines its actual market value. But, sometimes, even older vehicles with higher mileage are better than newer models with lower mileage but poor service history or condition. Therefore, we can assume that mileage is not that important, affecting the value of your car. However, most car models start to depreciate from their actual value if it completes 10,000 miles (or 16,093Kms) in a whole year.