The Mazda3 i comes standard with a 148-horsepower, 2.0-liter four-cylinder engine that can team with a five-speed manual or five-speed automatic transmission. Mazda3 s models use a 167-hp, 2.5-liter four-cylinder engine that works with a six-speed manual or five-speed automatic. The automatic includes a clutchless-manual mode that lets the driver control gear changes by nudging the console gear selector up or down.

A Mazda3 i with a manual transmission achieves the best EPA-estimated gas mileage, with its 25/33 mpg city/highway rating. Selecting the automatic lowers the city rating by 1 mpg. The Mazda3 s, meanwhile, is rated at 21/29 mpg with the manual and 22/29 mpg with the automatic.