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, general |
|---|---|
| Outer bounding box | No independently measured raw cavity envelope found. Only SAE cargo-volume figures (15.0 / 14.3 cu ft, conflicting) were confirmed, and SAE volume is a luggage-fit rating, not a usable rectangular envelope — do not surface it to a user as buildable box volume. |
| Known obstructions | Factory amplifier on Bose cars — reported passenger side of trunk behind the fuel pump bracket, but that placement is carried over from 2nd Gen sourcing and is NOT independently verified for this generation. Spare tire well. Rear wheel-well intrusions (not measured). On hybrid cars, an unquantified battery intrusion is the likely cause of the trunk-volume discrepancy above — its position and size were not established. |
Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.
| Subwoofers | 1x10" powered/compact sealed unit fed by a speaker-level-to-line-level converter tapped at the rear deck speakers on Bose cars, or a standard LOC at the rear speaker wiring on base 8-speaker cars. |
|---|---|
| Box type | sealed or powered enclosure |
| Location | trunk, kept clear of the passenger side until the amp location is confirmed on the actual car |
| Subwoofers | 1x12" sealed or 2x10" sealed, custom-built. No vehicle-specific molded enclosure found for this generation — custom-box car by default. The ~15 cu ft trunk is the roomiest of any LaCrosse and noticeably better to work with than the 2nd Gen's 13.3. |
|---|---|
| Box type | sealed, custom |
| Location | trunk. Confirm the amp position and, on a hybrid car, the battery intrusion before finalizing a box — both are unresolved in this entry and both could move the usable envelope. |
Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.
| Factory speaker size | 6.75" full-range — same as the 2nd Gen sibling, and independently corroborated by a real commercial upgrade kit (Kicker CSC654 6.5" package with adapters and harness) sold under 2014-2019 LaCrosse fitment. That product's year span deliberately straddles both LaCrosse generations, which is itself evidence the door opening did not change across the platform switch. |
|---|---|
| Known obstructions | Not documented. |
| Adapter bracket needed | yes — the named Kicker kit ships with adapters and a harness, confirming a 6.5" aftermarket driver needs a ring in this 6.75" opening |
| Tweeter | A-pillar — confirmed for this generation, matching the 2nd Gen sibling. This is one finding that genuinely DOES carry across the platform change. |
| Factory speaker size | not confirmed for this generation by any source. The 2nd Gen entry records 6.75" rear doors, and the same-size front doors plus the cross-generation Kicker fitment make it plausible the rears carried over too, but that is inference, not evidence, and it is not being written in as fact. |
|---|---|
| Known obstructions | Not documented. |
| Adapter bracket needed | unconfirmed |
| Tweeter | n/a — tweeters are front A-pillar only |
| Factory amp / premium audio | optional-on-some-trims — Bose. Documented split for this generation: the BASE system runs 8 speakers including A-pillar tweeters and rear-deck woofers; an 11-speaker Bose premium system was optional. Note the base count here (8) is higher than the 2nd Gen's base (7), so the two generations' trim structures are genuinely different and should not be conflated. AMP LOCATION IS THE WEAK POINT OF this entry: the only placement found (passenger side of trunk, behind the fuel pump bracket) is worded near-identically to the 2nd Gen sourcing and could not be independently confirmed for a 2017-2019 car. Treat it as a starting hypothesis to check on the actual vehicle, not as a verified location. |
|---|---|
| Adding subs without a head-unit swap | Yes. Same GM Bose architecture consideration as the companion entries: Bose amplifiers in this family take SPEAKER-LEVEL input, so use a speaker-level-to-line-level converter tapped at the rear deck speakers rather than a conventional RCA line output converter spliced between head unit and amp, which degrades the signal. On base 8-speaker cars a standard LOC at the rear speaker wiring is sufficient. CAVEAT, same as every Bose Buick : that guidance is GM-Bose-architecture guidance sourced from a GM Bose thread centered on a Chevrolet Malibu, not verified on a 3rd Gen LaCrosse. No wire colors confirmed for this generation. |
| Head unit | No replacement needed |
REAL UNRESOLVED FIGURE CONFLICT within a three-year run: 15.0 cu ft is reported for the 2019 car and 14.3 cu ft for the 2018 car by the same source set. A 0.7 cu ft swing inside one generation is more likely a hybrid/trim variant or a measurement-standard change than a real mid-cycle body change — this generation did offer a hybrid, which is the most probable explanation given that the 2nd Gen LaCrosse's eAssist variant cost it 2.5 cu ft for exactly that reason. NOT resolved and NOT averaged. If a builder's car is a hybrid, verify the trunk before designing anything tight. Either figure is a meaningful improvement over the 2nd Gen's 13.3 cu ft.
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.