To estimate the price of the 2021 BMW 320 I4 2.0L Twin Power Turbo Standard with 57000 km mileage, I first considered the selling price of a similar car with 30100 km mileage sold for SAR 120000 on 2024-02-02. Given the higher mileage of the target car, I adjusted the price downwards. Next, I looked at listed prices of similar cars: one with the same mileage listed for SAR 128000, and others with lower mileage listed between SAR 120000 and SAR 153000. The car with 116000 km was listed for SAR 87000, indicating a significant drop in value with higher mileage. Considering the target car's mileage and condition, I estimated its market price to be slightly lower than the selling price of the car with 30100 km but higher than the car with 116000 km.