BMW 3 Series vs Mazda 3: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Mazda 3 burns about $1,850 of fuel annually against $2,200 for the BMW 3 Series. 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 BMW 3 Series leads in both cycles — 31 mpg city and 43 mpg highway against 30 and 40 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the BMW 3 Series is recorded with 4 distinct engine configurations (SIDI & PFI; Mild Hybrid, SIDI, SIDI; PHEV), the Mazda 3 with 4 (SIDI, SIDI; With Cylinder Deactivation, SIDI; Without Cylinder Deactivation). Across 105 recorded BMW 3 Series configurations and 97 for the Mazda 3, 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 BMW 3 Series is offered with Rear-Wheel Drive, All-Wheel Drive, the Mazda 3 with 4-Wheel Drive, Front-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 BMW 3 Series emits 158 g/mile of CO2 versus 266 g/mile for the Mazda 3. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.