To estimate the price of the 2018 Ford Edge Ambiente (Base) with 100000 km mileage, I first looked at the selling price of a similar car: a 2016 Ford Edge V6 3.5L Trend (Mid) with 94000 km sold for SAR 59000 on 2023-09-30. Given the 2-year difference and the higher trim, I adjusted the price downwards. Next, I considered listed prices: a 2017 Ford Edge V6 3.5L Trend (Mid) with 87000 km was listed for SAR 64000, and a 2018 Ford Edge V6 3.5L Trend (Mid) with 55000 km was listed for SAR 79000. Adjusting for the base variant and higher mileage, I estimated a lower price. Additionally, a 2017 Ford Edge V6 3.5L Ambiente (Base) with 171000 km was listed for SAR 46000, which is a closer match in terms of variant but with much higher mileage. Considering all these factors, I arrived at the final estimate.