To estimate the price of the 2019 BMW 420 I4 2.0L Twin Power Turbo Standard sedan with 125200 km mileage, I considered the listed prices of similar cars. The closest match is a 2019 BMW 420 I4 2.0L Twin Power Turbo Standard sedan with 85834 km listed for SAR 123500. Given the higher mileage of the target car, I adjusted the price downwards. Other relevant listings include a 2020 model with 60000 km listed for SAR 108500 and a 2018 model with 56000 km listed for SAR 113500. Considering the average condition and higher mileage of the target car, I further adjusted the price downwards. The 2017 model with 130000 km listed for SAR 109000 also supports a lower estimate for the target car.