The previous Mazda3's cabin was starting to show its age, but the new Mazda3's interior features significant revisions that result in a contemporary cabin. The gauges have red illumination, and there's a dash-top screen that shows radio and air-conditioning settings. With the optional navigation system, the Mazda3 gets another screen for map information. The navigation system is operated by a cluster of buttons on the right side of the steering wheel.

With front bucket seats and a rear bench, the Mazda3 has room for five people. Cloth-covered seats are standard, but heated leather seats are optional. The 60/40-split rear backrest in both the sedan and hatchback folds down to expand the cargo area, which measures 11.8 cubic feet in the sedan and 17 cubic feet in the hatchback.

Standard features include a CD stereo with an auxiliary input jack, a tilt/telescoping steering wheel and power windows. Air conditioning is standard on all but the base, iSV trim. Cruise control and remote keyless entry are standard on all but the iSV and the iSport.