Audi A4 vs Infiniti Q50: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Audi A4 burns about $2,450 of fuel annually against $2,450 for the Infiniti Q50. 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 Infiniti Q50 is the stronger commuter at 29 mpg city, while the Audi A4 pulls ahead on the interstate at 37 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 A4 is recorded with 3 distinct engine configurations (SIDI; Mild Hybrid, SIDI, SIDI; FFV), the Infiniti Q50 with 4 (SIDI, 3.5, 2.0). Across 35 recorded Audi A4 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 A4 is offered with All-Wheel Drive, Front-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 Compact 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 Audi A4 emits 284 g/mile of CO2 versus 286 g/mile for the Infiniti Q50. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.