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 2012 Mercedes S600 V12 5.5L Twin Turbo Standard had an approximate price of 600,000 SAR, and considering a depreciation rate of 10% per year, the car would depreciate by 60,000 SAR each year. Over 12 years, the total depreciation would be 720,000 SAR. However, since the car cannot depreciate below a certain threshold, I will consider a minimum residual value of around 10% of the original price, which is 60,000 SAR. Given the car's average condition and high mileage, I will adjust the estimate slightly lower to account for these factors.