To estimate the price of the 2019 Mercedes GLE450 I6 3.0L Twin Turbo with 77000 km mileage, I considered the listed prices of similar cars. The closest match is a 2019 GLE450 with the same engine and mileage listed for SAR 249500. Other listings include a 2020 GLE450 Hybrid with 80000 km for SAR 290000, a 2020 GLE450 V6 with 100000 km for SAR 220000, a 2020 GLE450 V6 Twin Turbo with 51000 km for SAR 252000, a 2020 GLE450 V6 with 40000 km for SAR 259000, and a 2021 GLE450 V6 Twin Turbo with 29000 km for SAR 343000. Given the 2019 model year and similar mileage, the most relevant comparison is the 2019 GLE450 listed for SAR 249500. Considering depreciation and market trends, I adjusted the price slightly lower to reflect a realistic market value.