To estimate the price of the 2021 BMW 730 Li I4 2.0L Twin Power Turbo (Top) with 21000 km mileage, I first looked at the selling prices of similar cars. The 2022 model with 24000 km sold for 260000 SAR in April 2024, and another 2022 model with 55000 km sold for 249500 SAR in July 2024. These prices suggest a range of 249500-260000 SAR for a newer model with higher mileage. The 2020 model with 40000 km sold for 123500 SAR, indicating significant depreciation for older models. The listed prices for 2021 models range from 195500 to 277000 SAR, with the closest match (21000 km) listed for 225000 SAR. Considering the car's good condition and lower mileage, I estimate the market price to be slightly below the average of the listed prices and recent sales of newer models.