The BMW 328i cargo area accommodates a 6x9 inch speaker size in that location. Full-range units represent the compatible speaker types available for audio system use. These specifications cover the 2000 model year.
A single driver that reproduces bass through treble without a separate crossover network. It is the simplest replacement option and is common in factory audio systems.
Additional Notes
The cargo area of the 2000 BMW 328i accommodates a 6x9 inch speaker footprint, an oval format that requires an appropriately shaped mounting cutout and sufficient depth clearance behind the mounting surface to seat the basket and magnet assembly.
6x9 inch speakers carry a larger cone surface area than round mid-range formats, which allows greater air displacement and extended low-frequency reproduction within the cargo area enclosure.
The cargo area mounting position places speakers in a rear-firing or upward-angled orientation relative to the cabin, a location where low and mid-bass frequencies disperse broadly due to their longer wavelengths.
The oval geometry of a 6x9 inch driver creates a non-uniform dispersion pattern compared to a circular cone, with horizontal and vertical axis response diverging slightly at higher frequencies.
The BMW 328i cargo area + 6x9 inch full-range driver combination means a single transducer must handle the full audible spectrum from bass through treble without a crossover network directing frequencies to separate drivers.
Full-range speakers incorporate a main woofer cone alongside a smaller integrated tweeter element, allowing one unit to reproduce high-frequency content that a standard woofer cone alone would roll off.
The mounting depth available behind the cargo area panel is a critical spatial constraint for 6x9 inch drivers, as the larger magnet structures common in oval speakers demand greater rear clearance than smaller diameter units.
In a cargo area location, full-range drivers reproduce upper-midrange and treble frequencies at a greater distance from front-seat listening positions, which affects perceived imaging and high-frequency arrival time relative to dash-mounted or door-mounted speakers.