Mazda CX-9 vs Mercedes-Benz GLB-Class: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Mazda CX-9 burns about $2,550 of fuel annually against $2,700 for the Mercedes-Benz GLB-Class. That $150 yearly gap compounds to roughly $750 over five years and $1,200 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 Mercedes-Benz GLB-Class leads in both cycles — 25 mpg city and 33 mpg highway against 22 and 28 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the Mazda CX-9 is recorded with 2 distinct engine configurations (SIDI, 3.7), the Mercedes-Benz GLB-Class with 2 (SIDI; Mild Hybrid, SIDI). Across 16 recorded Mazda CX-9 configurations and 20 for the Mercedes-Benz GLB-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 Mazda CX-9 is offered with 4-Wheel Drive, Front-Wheel Drive, the Mercedes-Benz GLB-Class with Front-Wheel Drive, 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 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 Mercedes-Benz GLB-Class emits 311 g/mile of CO2 versus 362 g/mile for the Mazda CX-9. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.