Mercedes-Benz GLS-Class vs Subaru Outback: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Subaru Outback burns about $2,100 of fuel annually against $3,600 for the Mercedes-Benz GLS-Class. That $1,500 yearly gap compounds to roughly $7,500 over five years and $12,000 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 Subaru Outback leads in both cycles — 26 mpg city and 33 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 Mercedes-Benz GLS-Class is recorded with 2 distinct engine configurations (SIDI; Mild Hybrid, SIDI), the Subaru Outback with 3 (SIDI, 2.5, 3.6). Across 35 recorded Mercedes-Benz GLS-Class configurations and 26 for the Subaru Outback, 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 Mercedes-Benz GLS-Class is offered with All-Wheel Drive, 4-Wheel Drive, the Subaru Outback with All-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 Standard Sport Utility Vehicle 4WD and Small 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 Subaru Outback emits 308 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.