To estimate the price of the 2018 Cadillac ATS I4 2.0L Luxury (Mid) with 105000 km mileage and average condition, I first considered the selling price of a 2016 Cadillac ATS I4 2.5L Standard (Base) with 25000 km mileage and good condition, which sold for SAR 62000 on 2023-10-27. Given the 2-year difference and the higher trim and engine size of the target car, I adjusted the price upwards. Next, I looked at the listed prices of similar cars: a 2018 Cadillac ATS I4 2.0L Luxury (Mid) with the same mileage listed for SAR 69500, a 2018 Cadillac ATS I4 2.0L Turbocharged Premium Luxury (Mid+) with 60000 km listed for SAR 78500, and another 2018 Cadillac ATS I4 2.0L Luxury (Mid) with 160000 km listed for SAR 63500. Considering the average condition of the target car, I adjusted the price downwards from the listed prices. The final estimate balances these factors, considering the actual selling price, the listed prices, and the condition and mileage of the target car.