To estimate the price of the 2014 Mercedes E300 3.5L Standard with 300,000 km mileage, I first looked at the selling prices of similar cars. The closest match is a 2014 Mercedes E300 V6 3.5L with 131,500 km sold for AED 44,500 on 2024-08-02. Given the significant mileage difference, I adjusted the price downwards. Other relevant selling prices include a 2013 model with 155,100 km sold for AED 44,500 on 2024-05-18. For listed prices, a 2014 model with 251,200 km was listed for AED 42,000 but delisted on 2023-10-15, indicating it might have sold for less. Considering the high mileage of the target car and its condition, I further adjusted the price downwards from these benchmarks.