To estimate the price of the 2018 Hyundai Elantra I4 1.6L Smart (Base) with 257117 km mileage, I focused on the selling prices of similar cars. The closest match is the 2018 Hyundai Elantra I4 1.6L GL (Mid) with 208000 km sold for 39500 SAR in July 2023. Considering the target car is a base variant and has higher mileage, its value should be lower. Looking at 2016 models, a Smart (Base) with 297000 km sold for 28000 SAR in January 2024, and another with 167430 km sold for 31500 SAR in August 2023. Given the target car's higher mileage and average condition, I estimate its price to be slightly lower than these 2016 models. Therefore, I estimate the market price to be around 27000 SAR.