Given the lack of specific data points such as selling prices, offers accepted, and listed prices of similar cars, I will use the new car price and apply depreciation logic. Assuming a new 2023 BMW XM V8 650HP M Hybrid power (Top+) SUV has a price of 600,000 AED, and considering a depreciation rate of 10% per year, the car would depreciate by 60,000 AED in the first year. Since the car is one year old, the estimated price would be 600,000 AED - 60,000 AED = 540,000 AED. Additionally, the car has 21,000 km mileage and is in average condition, which might further reduce the price slightly. Factoring in these aspects, I estimate the price to be around 520,000 AED.