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 2018 Mercedes S650 Maybach V12 6.0L Twin Turbo V12 6.0L RWD (Top++) was priced at around 1,000,000 SAR, we apply a 10% depreciation per year. For a 6-year-old car (2024 - 2018), the depreciation would be 60%. Therefore, the estimated value would be 40% of the original price, which is 400,000 SAR. Considering the car's average condition and mileage, I will adjust the price slightly down to account for these factors.