GMC Terrain vs Mercedes-Benz GLS-Class: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the GMC Terrain burns about $2,200 of fuel annually against $3,600 for the Mercedes-Benz GLS-Class. That $1,400 yearly gap compounds to roughly $7,000 over five years and $11,200 over eight — often more than the price difference between two trims of the same vehicle, and the single largest running-cost line item separating these two.

City and highway economy: the GMC Terrain leads in both cycles — 28 mpg city and 39 mpg highway against 20 and 24 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the GMC Terrain is recorded with 3 distinct engine configurations (SIDI, 1.6, SIDI; FFV), the Mercedes-Benz GLS-Class with 2 (SIDI; Mild Hybrid, SIDI). Across 47 recorded GMC Terrain configurations and 35 for the Mercedes-Benz GLS-Class, the wider the engine spread the more the real-world fuel efficiency depends on which version you actually buy, so check the specific model year and drivetrain rather than the headline number.

Drivetrain and class: the GMC Terrain is offered with All-Wheel Drive, Front-Wheel Drive, the Mercedes-Benz GLS-Class with All-Wheel Drive, 4-Wheel Drive. All-wheel drive typically costs one to two mpg combined against the same vehicle in front- or rear-wheel drive, which is worth remembering when the gap between these two is small. The EPA classes them as Small Sport Utility Vehicle 2WD and Standard Sport Utility Vehicle 4WD respectively — the class drives the interior volume, cargo space and passenger space each one is measured against.

Tailpipe emissions: at their cleanest configurations the GMC Terrain emits 316 g/mile of CO2 versus 414 g/mile for the Mercedes-Benz GLS-Class. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.