Class Interior combined passenger and cargo volume index in cubic feet (liters)
Minicompact car < 85 (2407)
Subcompact car 85–99.9 (2407–2831)
Compact car 100–109.9 (2832–3114)
Midsize car 110–119.9 (3115–3397)
Large car ≥ 120 (3398)

Mazda 3 is 108.7 which makes it a compact