As this is a Mercedes-Benz GLS 450, it is thus powered by a Benz’s turbocharged 3.0-litre inline-6 cylinder engine with EQ Boost. 2020 Mercedes-Benz GLS 450 – Matt St-Pierre. How much does the Mercedes-Benz GLS Cost? The 2020 Mercedes-Benz GLS-Class GLS 450 4MATIC 4dr SUV AWD (3.0L 6cyl Turbo gas/electric hybrid 9A) can be purchased for less than the Manufacturer’s Suggested Retail Price (aka MSRP) of $76,195. Ranked at #17 in our fullsize suv of new cars. The new range-topping 2020 Mercedes-Benz GLS gets closer than ever to earning the luxury-focused S in its badge. The new 2020 Mercedes-Benz GLS 450 starts at $75950. That price is for the GLS 450 4Matic with a 3.0-liter … For the GLS, the mill … The 2020 Mercedes-Benz GLS has a starting price of $75,200, before destination fee. Read our in-depth review and buying advice.