Audi S3 vs Infiniti Q50: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Infiniti Q50 burns about $2,450 of fuel annually against $2,800 for the Audi S3. That $350 yearly gap compounds to roughly $1,750 over five years and $2,800 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 and highway economy: the Infiniti Q50 leads in both cycles — 29 mpg city and 36 mpg highway against 23 and 32 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the Audi S3 is recorded with 3 distinct engine configurations (SIDI, SIDI; Mild Hybrid, SIDI;), the Infiniti Q50 with 4 (SIDI, 3.5, 2.0). Across 11 recorded Audi S3 configurations and 60 for the Infiniti Q50, 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 Infiniti Q50 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 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 Infiniti Q50 emits 286 g/mile of CO2 versus 331 g/mile for the Audi S3. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.