Acura RDX vs Porsche Cayenne: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Acura RDX burns about $3,150 of fuel annually against $3,300 for the Porsche Cayenne. 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 versus highway split: the Acura RDX is the stronger commuter at 22 mpg city, while the Porsche Cayenne pulls ahead on the interstate at 29 mpg highway. If most of your driving is stop-and-go traffic the city figure is the one to weigh; for long-distance highway mileage the reverse is true, and the two vehicles effectively swap places depending on how you drive.

Powertrain choice: the Acura RDX is recorded with 2 distinct engine configurations (SIDI, 3.5), the Porsche Cayenne with 4 (SIDI, SIDI; PHEV, 4.0). Across 34 recorded Acura RDX configurations and 97 for the Porsche Cayenne, 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 Acura RDX is offered with All-Wheel Drive, Front-Wheel Drive, 4-Wheel Drive, the Porsche Cayenne 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 Small 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 Porsche Cayenne emits 174 g/mile of CO2 versus 370 g/mile for the Acura RDX. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.