The Kia K5 -- formerly known as the Optima -- arrives on the scene with a new name, a new look and new powertrain options. All of these work to not only differentiate it from its predecessor, but help it stand out in the crowded crop of competing midsize sedans.

The aesthetic is mostly new, but the K5's proportions aren't too far off those of the previous Optima. Overall, the sedan is about 2 inches longer with a 1.8-inch longer wheelbase. Cargo and passenger volume are within a few cubic inches of last year's numbers, too. The roofline is about an inch lower, which accentuates the more "Stinger-like" fastback profile. Along with the increased length, this gives the K5 a much more planted and menacing look than the Optima it replaces. However, unlike the Stinger, the K5 is not a liftback, retaining a trunk separated from the cabin. A chrome accent arcs from the base of the A-pillar all the way back to the rear of the vehicle -- a hallmark of the Optima design -- but now flows smoothly into the window graphic rather than just tapering off to an arbitrary point. 

Up front, the K5's "tiger nose" grille is flanked by amber LED daytime running lights with a zigzag design. The new sedan also ditches the old one's faux fender vents for a cleaner look. At the rear you'll find a new full-width LED taillight assembly that ties the design together nicely, making the sedan look wider despite being the same width as before.

My example is a midrange GT-Line model, which adds flashes of sporty flair without the performance upgrades of the more powerful, full-on K5 GT. The GT-Line features 18-inch alloy wheels, a gloss black rear spoiler and unique front and rear bumpers with LED foglights. Inside, there's a flat-bottomed steering wheel and unique SynTex leatherette upholstery on the seats.

1.6-liter turbo engine

Kia's 1.6-liter Smartstream turbo engine replaces the old 2.4-liter I4 as the K5's base engine, making 180 horsepower and 195 pound-feet of torque. That's 5 hp less than the 2.4-liter engine but, perhaps more importantly, a boost of 17 lb-ft, which keeps this engine feeling lively around town.

The 1.6T is paired with an eight-speed automatic transmission that feels like a good match for the engine. Together, they're not a supersporty pair -- particularly with the GT-Line's lack of paddle shifters -- but they do make an engaging duo that balances quiet performance in the Normal drive mode with smooth and ample thrust when flicked to Sport.

Driving the K5 is best described as light and easy. From the steering to the throttle response, the sedan feels light on its toes, nimble and not fatiguing. There's less feedback through the wheel than in a Honda Accord or Mazda6, which have better steering, but the Kia is nevertheless responsive. In a class where your options are usually either numb and detached or overly firm and "sport-tuned," the K5 stands apart as one of the good ones, a particularly balanced and joyful drive.

This year also marks the first time the Optima/K5 is available with all-wheel drive. Checking this box adds $3,700 to the bottom line because it also rolls in a premium equipment package. Of course, optioning all-wheel drive nudges the K5 fuel economy estimates down to 26 miles per gallon city, 34 mpg highway and 29 mpg combined, so if you live in a state where you don't need the extra grip, consider sticking with the front-wheel drive configuration, where most K5 models are good for a stated 27 city, 37 highway and 31 combined mpg. During my week of testing, I averaged 29.9 mpg with FWD. The base K5 LX model stands apart, gaining 1-2 mpg across the board versus the higher trims, most likely thanks to its lower weight and fewer creature comforts. 

If you want a higher level of performance, the K5 GT has a more powerful 2.5-liter engine with 290 hp and 311 lb-ft. I'll be evaluating that soon in a separate review, so stay tuned.

Excellent driver-assistance tech

The 2021 Kia K5 keeps current with the automaker's suite of standard safety and driver-aid technologies, with lane-departure warning, lane-keeping assist, forward precollision warning, pedestrian detection, driver alertness monitoring and automatic headlamp and high-beam systems fitted to every model. Kia's auto-light technologies are a touch too sensitive for my tastes, though; while driving around in broad daylight, I'll catch the headlamps momentarily activating if I pass under a dense tree or overpass, causing the map to flick from day to night mode, which is distracting. I also find the automatic high-beams annoying, activating even at low speeds on my reasonably illuminated residential street. 

On higher trim levels, blind-spot monitoring and rear cross-traffic alert are added to the feature set, and Kia's full-speed adaptive cruise control comes online as optional equipment. The latter works well, even at stop-and-go speeds, without any jerkiness when other vehicles merge into or out of my lane. These upper trim levels can also upgrade the emergency braking assist setup with cyclist detection and junction assist, which helps prevent collisions during cross-traffic (left-hand) turns.

Cabin tech: Bigger isn't always better

Kia's cabin tech is usually fairly straightforward and easy to understand, but 2021 adds a few odd details you'll want to keep an eye on. You can get the K5 with either an 8-inch or a 10.2-inch touchscreen infotainment system in the dashboard. Both run versions of the automaker's latest-generation UVO software, depending on trim and options chosen. Both are smartly organized and easy to use with features ranging from surprisingly useful (voice memo recorder) to sort of weird (ambient cafe sounds).

Both also feature standard Android Auto and Apple CarPlay. However, while the smaller unit has wireless connectivity for Android and Apple phones, the 10.25-inch model only connects via USB. For this reason alone, I'd personally stick with the smaller screen. The difference in visual real estate isn't huge, but the wireless phone connection is more convenient, making for a less cluttered cabin without dangling cables. It also makes the optional wireless phone charging slot a more compelling and useful upgrade. 

Of course, if you're planning on using the onboard software, this is less of a nit to pick. Kia's built-in navigation is pretty good and easy to use with natural language voice recognition and address input. The menu structure makes sense and is very easy to get around thanks to dedicated hardware shortcut buttons just below the screen leading to every major function.

Pricing and competition

The 2021 Kia K5 starts at $24,585 for the base LX (including $995 for destination), an increase of only $100 over last year's starting price. Considering the K5 comes with more standard equipment than the Optima, not to mention the once-optional upgrade to the turbocharged engine, I think it's worth the extra dough. 

While the thriftiest will be tempted by the LX's lower price and slightly better fuel economy, I think the sweet spot in the lineup is probably the front-drive GT-Line. It's slightly more expensive, starting at $26,485, but adds more standard features, looks better and has a higher level of safety equipment. Consider the optional $1,600 GT-Line Premium Package with its LED headlamps and interior lights, panoramic sunroof, wireless phone charger, smarter collision avoidance tech and stop-and-go adaptive cruise. As tested and so equipped, you're looking at $28,085 out the door. Drivers who need the surefootedness of all-wheel drive are looking at a still-reasonable $30,185 with the Premium pack.

That's about two grand less than a comparably equipped Toyota Camry -- with or without all-wheel drive -- with more engaging performance and easier-to-use tech. Honda's Accord is only available with front-wheel drive, yet manages to be more expensive than the K5 AWD. The Mazda6 is slightly cheaper and more fun to drive, but also boasts less space for people and cargo as well as a more spartan tech. 

The 2021 Kia K5 and the new Hyundai Sonata stand as my top picks in the affordable midsize sedan space, the Kia matching its cousin's tech, safety features, build quality and value. However, the K5 pulls ahead on more subjective metrics, with more palatable style and sharper performance.