The 2018 Mercedes-Benz GLS is a full-size luxury SUV designed to deliver three-row comfort, strong towing capability, and classic Mercedes refinement in a family-friendly package. It’s ideal for drivers who want premium materials, advanced safety tech, and real space for up to seven passengers without stepping up to an ultra-luxury brand. For 2018, the GLS continues the first-generation X166 platform (introduced for 2017 under the “GLS” name) and remains positioned as a flagship SUV beneath the G-Class, competing with vehicles like the BMW X7 (later), Range Rover, and Audi Q7.

- Three powerful engine choices: GLS 450 with a 3.0L twin-turbo V6 (362 hp), GLS 550 with a 4.7L twin-turbo V8 (449 hp), and the high-performance AMG GLS 63 with a 5.5L twin-turbo V8 (577 hp). All pair with a 9-speed automatic and standard 4MATIC all-wheel drive. - Spacious three-row interior with available power-folding third row, generous cargo room for a full-size SUV, and upscale Mercedes materials and seating comfort. - AIRMATIC air suspension available on many trims, delivering a smooth ride quality and adjustable ride height that helps in poor weather and on rough roads. - Strong capability for its class, including confident highway manners and solid towing potential when properly equipped (often up to around 7,500 lbs depending on configuration). - Available driver assistance features (depending on package) such as adaptive cruise control, lane keeping support, blind spot monitoring, parking sensors, and surround-view camera systems.

Shoppers searching “2018 Mercedes-Benz GLS reliability” should expect a generally solid luxury SUV with above-average complexity. Many owners report good long-term comfort and drivability, but repairs can be expensive and certain systems can be trouble spots as mileage climbs. - AIRMATIC air suspension leaks or compressor issues: On vehicles equipped with air suspension, owners sometimes report sagging overnight, uneven ride height, or a “vehicle rising slowly” symptom. This can show up around 60,000–100,000 miles, with air struts, valve blocks, or compressors being common culprits. - Turbocharged engine oil leaks and cooling system seepage: The V6 and V8 models can develop oil seepage from seals/gaskets over time, and some owners report coolant leaks from hoses or fittings as the vehicle ages. These issues often appear in the 50,000–90,000-mile range and are important to address early to avoid bigger problems. - Electrical and infotainment glitches: Reports include intermittent warning lights, parking sensor/camera hiccups, battery/auxiliary battery warnings, and COMAND infotainment bugs. These aren’t always constant failures, but they can be frustrating and may require software updates, battery replacement, or diagnostic time. - Brake wear and vibration complaints: Due to the GLS’s size and weight, brakes can wear faster than drivers expect, and some owners notice pulsation or vibration under braking if rotors warp. Brake service needs vary widely, but some drivers encounter brake work before 40,000–60,000 miles depending on driving style.