Audi A6 vs Subaru Legacy: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Subaru Legacy burns about $2,050 of fuel annually against $2,650 for the Audi A6. 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 versus highway split: the Subaru Legacy is the stronger commuter at 27 mpg city, while the Audi A6 pulls ahead on the interstate at 38 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 A6 is recorded with 3 distinct engine configurations (SIDI, SIDI; Mild Hybrid, 3.0), the Subaru Legacy with 3 (SIDI, 2.5, 3.6). Across 36 recorded Audi A6 configurations and 16 for the Subaru Legacy, 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 A6 is offered with All-Wheel Drive, 4-Wheel Drive, Front-Wheel Drive, the Subaru Legacy 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 Midsize Cars and Midsize 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 Subaru Legacy emits 295 g/mile of CO2 versus 311 g/mile for the Audi A6. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.