What we researched for this specific generation: where an enclosure actually fits, what the factory speakers are, how the factory audio is wired, and which real builds and commercial products exist for it. Confidence badges say how well each figure is sourced — this is research, not manufacturer spec.
Body styles covered: 4-Door Sedan
These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.
| Location | trunk side compartment |
|---|---|
| Outer bounding box | sized to the named 10"/12" custom enclosure product, no independent raw dimension published. Infinite Autowerks' G20/G80 side-compartment enclosure, a lower bound on this cavity: 0.7 ft3 for a 10" sub, 1.0 ft3 for a 12", maximum subwoofer mounting depth 6.5", built to fit the trunk's side compartment; no outside dimensions or model years published. For scale, BMW's US 2019 launch kit gives the whole trunk as 17.0 cu ft (BMW does not say which measurement standard); that is the trunk, not this compartment. |
| Known obstructions | iDrive 7.0 cars: factory RAM module occupies part of the trunk electronics space and cannot be relocated |
Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.
| Subwoofers | compact powered sub with an MGU-compatible LOC/amp |
|---|---|
| Box type | aftermarket, trunk side compartment |
| Location | trunk side compartment |
| Subwoofers | Infinite Autowerks 10"/12" custom enclosure |
|---|---|
| Box type | custom, sealed |
| Location | trunk side compartment |
Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.
| Adapter bracket needed | unconfirmed |
|---|---|
| Tweeter | Mirror triangles and instrument panel on the base Hi-Fi system: BMW's UK equipment list (option 676, from 03/19 production) gives "3 tweeters in the mirror triangles and instrument panel", so the base car does have front tweeters at the mirror/pillar position. An owner-sourced note said the base Hi-Fi lacked the A-pillar tweeter and only Harman Kardon added it; BMW's own list contradicts that. Harman Kardon tweeter positions on this sedan were not read. Exact diameter not confirmed. UK-market list; the US list was not read. |
| Midrange | Front door trims, on the Hi-Fi system: BMW's UK equipment list (Hi-Fi option 676) lists "4 midrange speakers in the front and rear door trims"; no size given. UK-market list; the US list was not read. Whether the Harman Kardon system changes the door layout on this sedan was not read. |
| Adapter bracket needed | unconfirmed |
|---|---|
| Tweeter | Rear door-mounted on the Harman Kardon tier per owner reports, alongside a pair of midrange+tweeter units they place at the rear shelf. Owner-sourced: BMW's Harman Kardon list for this sedan was not read (on the X5 G05 the same option puts the rear tweeters in the rear door trims and the D-pillar). BMW's Hi-Fi list (option 676) has no rear tweeters. |
| Midrange | Rear door trims, on the Hi-Fi system: BMW's UK equipment list (Hi-Fi option 676) lists "4 midrange speakers in the front and rear door trims"; no size given. UK-market list; the US list was not read. The rear-shelf pair owners report on Harman Kardon cars is listed separately. |
| Factory amp / premium audio | Two confirmed tiers: base Hi-Fi (S676A) and Harman Kardon (S688A). A specialized amplifier product ('Alpha One Amp for MGU Harman Kardon,' BimmerTech) exists specifically for BMWs with the MGU head unit and S688A HK option — evidence this integration is involved enough that BMW-specific commercial products exist for it, unlike most other brands. BMW's US 2019 launch kit: the standard hi-fi system has 10 speakers and a 205-watt amplifier; the optional Harman Kardon surround system has 16 speakers and a digital seven-channel amplifier with 464 watts. |
|---|---|
| Adding subs without a head-unit swap | Confirmed possible, but genuinely more involved than most vehicles here — requires identifying iDrive 6.0 vs. 7.0 electrical architecture first, since the correct integration approach differs (conventional amp swap vs. amp-alongside-RAM). |
| Head unit | No replacement needed |
Confirmed factory audio tiers: base Hi-Fi (option code S676A) vs. the top Harman Kardon system (option code S688A) — genuine BMW factory option codes, not just marketing names. Commercial fitment found: Infinite Autowerks sells a custom 10" or 12" subwoofer enclosure specifically shaped to fit the trunk's side compartment on this generation (shared platform code with the G80 M3), maximizing usable trunk floor space. Important integration complexity confirmed: this generation's electrical architecture depends on which head unit variant is fitted — iDrive 6.0 cars have a conventional removable factory amp accessible via the trunk wheel-arch trim; iDrive 7.0 cars instead use a RAM (receiver) module that CANNOT be removed like a standard amp, so an aftermarket amp must be installed alongside it rather than replacing it. This is a BMW-specific wrinkle not seen on the mainstream-brand vehicles on other vehicles covered here.
Outside links. Some are commercial products, some are owner builds posted on forums — the label says which. We do not endorse any of them.
Each link opens the tool with this vehicle already selected.
Measure your own vehicle. Trim levels, factory subwoofer options, and mid-generation changes all move these numbers, and a box cut to a researched figure that does not match your truck is wasted wood. Where a badge reads Unconfirmed, treat the value as a starting point for your own measurement, not as an answer.