BMW iX vs Cadillac OPTIQ: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Cadillac OPTIQ burns about $700 of fuel annually against $800 for the BMW iX. That $100 yearly gap compounds to roughly $500 over five years and $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 versus highway split: the Cadillac OPTIQ is the stronger commuter at 117 mpg city, while the BMW iX pulls ahead on the interstate at 94 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.

Drivetrain and class: the BMW iX is offered with All-Wheel Drive, the Cadillac OPTIQ with Rear-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 Standard Sport Utility Vehicle 4WD and Standard Sport Utility Vehicle 2WD respectively — the class drives the interior volume, cargo space and passenger space each one is measured against.