The BMW i8 rear location accommodates a 6x9 inch speaker size across all listed model years. Compatible types for the audio system include full-range units. These specifications cover the 2014 to 2017 range of model years.
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 rear speaker location in the BMW i8 accommodates a 6x9 inch footprint across the 2014 through 2017 model years.
A 6x9 inch speaker occupies a notably elongated oval cavity, which requires adequate depth clearance behind the mounting surface to house the basket and magnet assembly without obstruction.
The rear placement of the BMW i8's speaker location positions the drivers behind the occupants, a geometry that affects stereo imaging and the perceived directional origin of reproduced sound.
6x9 inch drivers carry a larger cone surface area than smaller round formats, which translates to greater air displacement and stronger output in the lower midrange and upper bass frequencies at the rear of the cabin.
The elongated cone geometry of a 6x9 inch unit influences the dispersion pattern of mid and high frequencies, generally narrowing horizontal projection compared to a circular cone of similar surface area.
Full-range speakers are designed to reproduce the entire audible frequency spectrum-bass, midrange, and treble-within a single driver unit, sometimes assisted by an integrated passive crossover and tweeter.
In a rear location, a full-range driver handles low-frequency reinforcement as well as midrange vocal and high-frequency detail without requiring a separate crossover network or additional speaker components at that position.
The 6x9 inch format is particularly suited to rear deck or rear panel installations because the available footprint in such locations tends to be larger than door apertures, accommodating the elongated mounting ring of the driver.
Full-range compatibility at the rear of the BMW i8 indicates the location is served by a single driver type rather than a component system split between woofer and tweeter elements.