Audi S4 vs Subaru WRX: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Audi S4 burns about $3,150 of fuel annually against $3,150 for the Subaru WRX. That $0 yearly gap compounds to roughly $0 over five years and $0 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 Subaru WRX is the stronger commuter at 21 mpg city, while the Audi S4 pulls ahead on the interstate at 30 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 Audi S4 is recorded with 1 distinct engine configuration (SIDI), the Subaru WRX with 2 (SIDI, 2.5). Across 12 recorded Audi S4 configurations and 32 for the Subaru WRX, 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 Audi S4 is offered with All-Wheel Drive, 4-Wheel Drive, the Subaru WRX 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 Compact Cars and Compact Cars respectively — the class drives the interior volume, cargo space and passenger space each one is measured against.

Tailpipe emissions: at their cleanest configurations the Audi S4 emits 363 g/mile of CO2 versus 374 g/mile for the Subaru WRX. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.