Infiniti QX50 vs Lexus RX: 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 $2,800 for the Infiniti QX50. That $700 yearly gap compounds to roughly $3,500 over five years and $5,600 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 Lexus RX leads in both cycles — 37 mpg city and 34 mpg highway against 24 and 31 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the Infiniti QX50 is recorded with 3 distinct engine configurations (SIDI & PFI, SIDI & PFI; VCR, 3.7), the Lexus RX with 4 (SIDI & PFI, SIDI & PFI; Hybrid, SIDI & PFI; PHEV). Across 20 recorded Infiniti QX50 configurations and 59 for the Lexus RX, 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 Infiniti QX50 is offered with Front-Wheel Drive, All-Wheel Drive, Rear-Wheel Drive, the Lexus RX with Front-Wheel Drive, 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 Small Sport Utility Vehicle 2WD 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 336 g/mile for the Infiniti QX50. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.