To estimate the price of the 2014 Mercedes S500 V8 4.7L Twin Turbo with 198000 km mileage, I analyzed the listed prices of similar cars. The closest match is a 2014 Mercedes S500 V8 4.7L Twin Turbo with the same mileage listed for SAR 173500. Other relevant data points include a 2014 S500 V8 4.7L AMG with 172000 km listed for SAR 188000, and a 2014 S500 V8 4.7L with 251000 km listed for SAR 130000. Considering the condition and mileage of the target car, I adjusted the price slightly below the average of these listings to account for the higher mileage and the fact that listed prices are often higher than actual selling prices.