To estimate the price of the 2018 Kia Optima I4 2.4L LX (Mid) with 59171 km mileage, I first considered the selling price of a 2016 Kia Optima I4 2.0L GDI (Base) with 290000 km mileage, which sold for SAR 26500 in February 2024. Given the significant mileage difference and the fact that the target car is a higher trim and newer, this selling price serves as a lower bound. Next, I looked at the listed prices of similar cars. The closest match is a 2018 Kia Optima I4 2.4L LX (Mid) with the same mileage listed for SAR 51000. Other relevant listings include a 2018 Kia Optima I4 2.4L GDI (Base) with 122500 km listed for SAR 47000 and a 2018 Kia Optima I4 2.4L LX (Mid) with 183000 km listed for SAR 44000. Considering the target car's lower mileage and average condition, I adjusted the price downwards from the highest listed price of SAR 51000 to account for negotiation and market conditions.