Audi S3 vs BMW 8 Series: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Audi S3 burns about $2,800 of fuel annually against $3,050 for the BMW 8 Series. That $250 yearly gap compounds to roughly $1,250 over five years and $2,000 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 BMW 8 Series is the stronger commuter at 23 mpg city, while the Audi S3 pulls ahead on the interstate at 32 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 S3 is recorded with 3 distinct engine configurations (SIDI, SIDI; Mild Hybrid, SIDI;), the BMW 8 Series with 1 (SIDI). Across 11 recorded Audi S3 configurations and 64 for the BMW 8 Series, 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 S3 is offered with All-Wheel Drive, the BMW 8 Series with All-Wheel Drive, Rear-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 Subcompact Cars and Subcompact 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 S3 emits 331 g/mile of CO2 versus 347 g/mile for the BMW 8 Series. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.