Given the lack of specific data points such as selling prices, offers accepted, and listed prices, I will use the new car price and apply depreciation logic. Assuming a new 2021 BMW 318 Standard sedan has a price of 200,000 AED, and considering a depreciation rate of 10% per year, the car would depreciate by 20% over two years. This results in a depreciation of 40,000 AED, making the estimated price 160,000 AED. Additionally, considering the car's mileage of 50,000 km, which is relatively high for a three-year-old car, I will further reduce the price by 10,000 AED to account for the higher mileage and potential wear and tear, resulting in a final estimate of 150,000 AED.