Kia K5 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 $1,900 for the Kia K5. That $50 yearly gap compounds to roughly $250 over five years and $400 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 Mazda 3 leads in both cycles — 30 mpg city and 40 mpg highway against 29 and 38 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the Kia K5 is recorded with 4 distinct engine configurations (SIDI & PFI, SIDI & PFI; Stop-Start, SIDI), the Mazda 3 with 4 (SIDI, SIDI; With Cylinder Deactivation, SIDI; Without Cylinder Deactivation). Across 26 recorded Kia K5 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 Kia K5 is offered with All-Wheel Drive, Front-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 Large 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 Mazda 3 emits 266 g/mile of CO2 versus 277 g/mile for the Kia K5. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.