BMW Z4 vs Mazda MX-5: Specs Compared

Running cost over five years: at the EPA's 15,000-mile-a-year assumption the Mazda MX-5 burns about $2,550 of fuel annually against $2,700 for the BMW Z4. That $150 yearly gap compounds to roughly $750 over five years and $1,200 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 MX-5 leads in both cycles — 27 mpg city and 36 mpg highway against 25 and 33 mpg — so its fuel-efficiency advantage holds whether you commute in traffic or cover long highway miles.

Powertrain choice: the BMW Z4 is recorded with 1 distinct engine configuration (SIDI), the Mazda MX-5 with 2 (SIDI, 2.0). Across 25 recorded BMW Z4 configurations and 25 for the Mazda MX-5, 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 Z4 is offered with Rear-Wheel Drive, the Mazda MX-5 with 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 Two Seaters and Two Seaters 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 MX-5 emits 298 g/mile of CO2 versus 312 g/mile for the BMW Z4. Emissions track fuel consumption almost exactly, so the cleaner vehicle here is also the cheaper one to fuel.