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 |
|---|---|
| Outer bounding box | No independently measured trunk dimensions found. Zenclosures prints no outside dimensions for its Optima box (0.89 ft3 per chamber, 9.00" mounting depth). |
| Known obstructions | Zenclosures: "Will not fit Hybrid" (the hybrid's trunk is smaller in EPA's data, 10-11 cu ft). Kia lists "Infinity audio with external amplifier and subwoofer" as an option on the 2013 EX and SX; where the amplifier and subwoofer sit was not found. |
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 | Kia's specification and features pages name no door speaker size; Metra does not cover Kia |
|---|---|
| Adapter bracket needed | unconfirmed |
| Factory speaker size | same gap as the front doors |
|---|---|
| Adapter bracket needed | unconfirmed |
| Factory amp / premium audio | Kia's own pages, by model year. 2011 (Kia's model-year overview text, not a features table): an eight-speaker Infinity premium audio system comes with the LX and EX Technology Packages, alongside navigation and a back-up camera; the standard radio is AM/FM/CD/MP3 with SIRIUS satellite capability. 2012 (overview text): the eight-speaker Infinity system is standard in the Premium Package on the EX, EX Turbo and SX, and part of the LX Technology Package. 2013 (features table): AM/FM/CD/MP3/SiriusXM standard on the LX, EX and SX; "Infinity surround-sound audio with eight speakers" optional on all three; "Infinity audio with external amplifier and subwoofer" (with UVO and HD Radio) optional on the EX and SX, not offered on the LX. 2014 and 2015 (features tables): "6 speakers with door-mounted tweeters" standard on the LX, EX and SX; the eight-speaker Infinity system optional on the EX and SX, not offered on the LX. Turbo trims were not compared. Kia gives no speaker sizes, watts, or amplifier and subwoofer locations. |
|---|---|
| Adding subs without a head-unit swap | no Optima-specific integration information found |
One sealed Zenclosures design: 0.89 ft3 per chamber, 9.00" mounting depth, slides in through the trunk opening below the rear dash; "Will not fit Hybrid". Kia's own trunk figure is 15.4 cu ft, the same on the LX, EX and SX: labelled "SAE Volume, trunk" for 2015 and "Cargo volume (rear seat up)" for 2013 and 2014. Kia's media site has no 2011 or 2012 specification page, so no Kia figure covers those years. EPA's luggage figure for the conventional sedan is 15 cu ft in 2011, 2013 and 2015 (the Optima Hybrid is 10-11). Luggage ratings, not box dimensions. No measured trunk dimensions were found. Measure your own trunk before cutting wood.
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.