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: Minivan
These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.
| Location | cargo area behind the third row |
|---|---|
| Outer bounding box | Maker-published, not a measured usable cavity: Toyota's December 2009 release introducing the 2011 Sienna says that with the third row stowed and the second row removed "the cargo area is approximately eight feet long and four feet wide". That describes the whole van in that configuration, not the space behind an upright third row, for which no dimensions were found. |
| Known obstructions | None documented in the pages read. Toyota 2009: the figure above assumes "third row stowed" and the second row removed. |
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 |
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| Adapter bracket needed | unconfirmed |
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| Factory amp / premium audio | Toyota, by grade and year. 2011 (US releases dated 2009-12-02 and 2009-12-18): Sienna and LE "AM/FM CD player with four speakers"; LE V6 "AM/FM/MP3 CD player" (no speaker count); XLE (optional) "10-speaker JBL premium sound system with voice-activated DVD Navigation". Toyota Canada 2011 features: 4-speaker CD player; 6-speaker CD player; "JBL Audio, AM/FM CD/MP3/WMA In-Dash 4-Disc Changer, 10-Speakers". 2015 (US pricing release 2014-09-02): "four different Entune audio systems"; Limited and Limited Premium "Entune Premium JBL Audio with Navigation and App Suite that features 10 speakers including a subwoofer"; LE "Entune Audio Plus with 7-inch touchscreen". Toyota Canada 2015: rows "4-Speakers 6-Speakers 10-Speakers" and "JBL AM/FM/CD Player". No wattage; the JBL system is the only one with a stated subwoofer. 2012 to 2014 and 2016 to 2020 not read. |
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Toyota Canada 2011 and 2015 specification tables ("Cargo Capacity"): "4.25 (150.0) Behind Front Seats - Max.", "2.47 (87.1) Behind 2nd Row Seats - Max.", "1.11 (39.1) Behind 3rd Row Seats - Max.". Toyota USA 2009-12-18 release (third row stowed, second row removed): "the cargo area is approximately eight feet long and four feet wide"; with the third row in use "there is enough storage for five golf bags or four large suitcases". No SAE or EPA label printed; the US releases carry no cubic-foot figure. No height, opening width or wheel-housing width. Toyota Canada's tables print a metric figure with Toyota's cubic-foot figure in brackets (cubic metres in 2011, litres in 2015); they are Canadian documents, and a US Toyota page may differ. No box made for a 2011-2020 Sienna was found from the box makers checked.
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.