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

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Subaru Ascent burns about $2,650 of fuel annually against $3,600 for the Mercedes-Benz GLS-Class. That $950 yearly gap compounds to roughly $4,750 over five years and $7,600 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 Ascent leads in both cycles — 21 mpg city and 27 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 Ascent with 1 (SIDI). Across 35 recorded Mercedes-Benz GLS-Class configurations and 18 for the Subaru Ascent, 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 Ascent 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 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 Subaru Ascent emits 384 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.