Lexus RX vs Mercedes-Benz GLB-Class: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Lexus RX burns about $2,100 of fuel annually against $2,700 for the Mercedes-Benz GLB-Class. That $600 yearly gap compounds to roughly $3,000 over five years and $4,800 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 Lexus RX leads in both cycles — 37 mpg city and 34 mpg highway against 25 and 33 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the Lexus RX is recorded with 4 distinct engine configurations (SIDI & PFI, SIDI & PFI; Hybrid, SIDI & PFI; PHEV), the Mercedes-Benz GLB-Class with 2 (SIDI; Mild Hybrid, SIDI). Across 59 recorded Lexus RX 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 Lexus RX is offered with Front-Wheel Drive, All-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 Lexus RX emits 89 g/mile of CO2 versus 311 g/mile for the Mercedes-Benz GLB-Class. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.