To estimate the price of the 2015 Nissan X-Trail I4 2.5L S AWD (7-Seater) (Mid+), I first considered the selling prices of similar cars. A 2015 X-Trail S 2WD (7-Seater) (Base+) with 169076 km sold for 49000 SAR in good condition, and a 2015 X-Trail S AWD (5-Seater) (Mid) with 148000 km sold for 43500 SAR in good condition. The target car is in average condition, so its value should be lower. A 2015 X-Trail SV X-Treamer AWD (Top) with 148000 km in average condition sold for 44500 SAR, indicating a higher trim level. A 2015 X-Trail S 2WD (7-Seater) (Base+) with 229600 km in average condition sold for 35000 SAR recently, which is a closer match in condition and mileage. Considering the target car's AWD feature and 171000 km mileage, I estimate its value slightly higher than 35000 SAR but lower than 43500 SAR. The listed price of a similar car was 40000 SAR, which aligns with this range. Therefore, I estimate the market price to be around 38000 SAR.