The mild redesign received by the Optima last year yielded improved comfort for the already-spacious interior. Front headroom can be tight with the available sunroof, and the Optima still doesn’t have very supportive seats, but it does claim one of the roomiest cabins in its segment, with good backseat legroom and headroom.
Car and Driver generally likes the front seats, saying that "posteriors in front sink into buckets with a cushy top layer akin to a pillow-top mattress," although they add that "side support is wanting." ConsumerGuide agrees that the seats "offer little lateral support in turns," but asserts that the front seats provide "sufficient legroom and adequate headroom for tall drivers," although taller passengers will be disappointed to learn that the "mediocre headroom is diminished further by the sunroof housing."
Edmunds contends that while the cabin is spacious, "seat bottoms are a little short” in back, “offering less support for long-limbed occupants than many rivals' accommodations." ConsumerGuide also points out that "knee space grows tight if the front seats are far back," but generally reviewers note there’s adequate space for adults in back.
There’s also a big 14.8-cubic-foot trunk that will swallow more gear than most of the Optima's competitors. ConsumerGuide finds that the Kia Optima offers a "decent-size trunk [that] has hinges that don't intrude into cargo space," while Edmunds says that "trunk capacity is 14.8 cubic feet, and all Kia Optimas have a 60/40-split-folding rear seat."
Storage is good inside, with ConsumerGuide mentioning an “ample glovebox, door map pockets, and an armrest console."
Up close, cabin materials are a bit dull, but the stark simplicity and quality materials will clearly be appreciated by some. Kelley Blue Book also reports that "even in base LX form, the Optima's interior materials rate well above merely acceptable," and on "those cars with leather we were impressed by the leather's tone and its perforated texture." Edmunds says that the Optima's "interior materials as a whole give an impression of quality," while Cars.com mentions that the Kia Optima SX gets "electroluminescent gauges, custom leather seats and metallic trim."
TheCarConnection.com finds a range of reviewer comments about engine noise. Although Car and Driver claims that the four-cylinder “mostly hums quietly to itself and winds to high revs without major vibes," while ConsumerGuide says that it “emits a thrashy groan at full throttle." That source remarks that the V-6 is “less refined than most rivals V-6s," but the quieter of the two.