2021 Hyundai Sonata vs. 2021 Kia K5 Comparison

Erin Riches-Wong | Apr 21, 2021

Together the Hyundai Sonata and Kia K5 (formerly known as the Optima) account for a healthy portion of sales in the midsize sedan class. And consumers who buy either of these medium-size sedans often come away with a high level of satisfaction.

The Sonata ranked first among midsize cars in the J.D. Power 2020 Automotive Performance, Execution and Layout (APEAL) Study. This study measures owners' emotional attachment and level of excitement with their new vehicle across 37 attributes, ranging from the sense of comfort and luxury they feel when climbing into the driver's seat to the feeling they get when they step on the accelerator.

The K5's Optima predecessor ranked third in this study, which was based on survey data collected after 90 days of ownership.

These rankings make sense when you get behind the wheel of a 2021 Hyundai Sonata or 2021 Kia K5. Owners love the way these sedans look inside and out, and the combination of design and materials makes you feel like you spent more than you did.

Hyundai and Kia also lead this class in advanced driver assistance technology, both in quantity of features and how well everything works. And no matter which trim level you choose, you're going to end up with a large, useful infotainment display with smartphone integration.

If technology and design matter to you in a midsize sedan, these cars should be on your short list. Here's a 2021 Honda Sonata vs. 2021 Kia K5 comparison to help with your research.

Price and Value

2021 Hyundai Sonata Limited Silver Front Quarter

2021 Hyundai Sonata Limited

Consumers shopping for a 2021 Hyundai Sonata will find that this midsize sedan ranges in price from $23,950 to $33,950, not including a $1,005 destination charge. Trim levels are SE, SEL, SEL Plus, N Line, and Limited.

Hyundai offers three different 4-cylinder engines on the 2021 Sonata. Any of them will get you to work, but the high-performance engine on the Sonata N Line will quicken your pulse as well.

Alternatively, you might consider the 2021 Hyundai Sonata Hybrid, which combines yet another 4-cylinder engine with an electric motor and a small battery pack. The hybrid Sonata ranges in price from $27,750 to $35,300. Trim levels for the Sonata Hybrid are Blue, SEL, and Limited.

Hyundai offers connected services starting at the SEL trim level on the standard Sonata and the Blue trim level on the Sonata Hybrid.

Known as Hyundai Blue Link, this suite of connected car services is complimentary for the first three years that you own a Sonata. With the Blue Link app installed on your phone, you can lock the doors and start the engine remotely, as well as receive notifications for warning lights and required maintenance. You can also send commands to your car using Amazon Alexa or Google Assistant.

In addition, a vehicle locator feature can help you find your Sonata in unfamiliar parking facilities, and you can set geofencing parameters if you lend your car to a less experienced driver. If your Hyundai has factory navigation, you can seamlessly share destinations to the car from your phone.

Hyundai Blue Link also has your back in stressful situations. It includes automatic collision notification, live emergency assistance, rapid access to roadside help, and a stolen vehicle locator feature (that can immobilize the engine until your Sonata has been recovered).

Unlike some other midsize sedans, the Sonata does not offer a built-in Wi-Fi hotspot.

If you're looking for complimentary scheduled maintenance, though, you'll be happy to note that it's on the house for the first three years that you own a Sonata. 

Consumers researching the 2021 Kia K5 will find that it ranges in price from $23,590 to $30,590, not including a $995 destination charge. Trim levels are LX, LXS, GT-Line, EX, and GT.

Kia offers just two 4-cylinder engines on the K5. Most buyers will be content with the standard engine, but those with a greater need for speed will want to check out the K5 GT, which shares its powertrain with the Sonata N Line.

There's no hybrid version of the Kia K5, at least not for the 2021 model year. But unlike the Sonata, the K5 has an optional all-wheel-drive (AWD) system.

Note that AWD is a package option on the K5 LXS and GT-Line (not the GT) trim levels, so you have to buy it in combination with other features. It costs $2,100 extra on the LXS, but you'll spend $3,700 more to add it to the GT-Line.

Save for the base LX, every 2021 Kia K5 offers one year of complimentary connected services. Kia UVO offers all the same features you get with Blue Link on the 2021 Sonata. And as on the Hyundai, there is no Wi-Fi.

If you decide not to buy a subscription package when the 12-month trial expires, your K5 will revert to UVO Lite, which provides automatic collision notification and maintenance reminders for an additional 4 years free of charge.

Kia does not offer free scheduled maintenance for the K5.

Advantage: Hyundai Sonata

Reliability and Quality

2021 Kia K5 GT Blue Front Quarter

2021 Kia K5 GT

The Hyundai Sonata ranked second in the J.D. Power 2021 Vehicle Dependability Study but did not rank in the 2020 Initial Quality Study. The 2021 Hyundai Sonata comes with the following warranty and roadside assistance coverage:

  • Standard warranty: 5 years or 36,000 miles
  • Powertrain warranty: 10 years or 100,000 miles
  • Hybrid system warranty: 10 years or 100,000 miles
  • Hybrid battery warranty: 10 years or 100,000 miles (10 years or 150,000 miles in California emissions states)
  • Roadside assistance: 5 years and unlimited mileage

The Kia K5's predecessor, the Optima, ranked first among midsize cars in the J.D. Power 2021 Vehicle Dependability Study. It also ranked third in the 2020 Initial Quality Study. The 2021 Kia K5 comes with the following warranty and roadside assistance coverage:

  • Standard warranty: 5 years or 60,000 miles
  • Powertrain warranty: 10 years or 100,000 miles
  • Roadside assistance: 5 years or 60,000 miles

Advantage: Kia K5

Performance and Efficiency

2021 Hyundai Sonata Limited Interior Dashboard

2021 Hyundai Sonata Limited

You have four different powertrains to consider if you're shopping for a 2021 Hyundai Sonata.

The Sonata SE and SEL come with a 2.5-liter 4-cylinder engine rated at 191 horsepower and 181 pound-feet of torque. An 8-speed automatic transmission is standard. All 2021 Sonatas are front-wheel-drive regardless of the engine under the hood.

Next up is a turbocharged, 1.6-liter 4-cylinder engine known as the 1.6T. It makes slightly less horsepower with just 180, but its 195 pound-feet of torque are available at much lower engine speeds and this translates to brisker acceleration. The 1.6T engine is standard on the SEL Plus and Limited, and it also comes with an 8-speed automatic.

If that's not enough for you, Hyundai has added the Sonata N Line to the lineup for 2021. The N Line has a turbocharged, 2.5-liter 4-cylinder engine that generates 290 hp and 311 pound-feet of torque. This special Sonata also has an 8-speed, dual-clutch automated manual transmission that provides the convenience of a conventional automatic while providing the more responsive shifts associated with a true manual transmission. 

Your other option is the hybrid Hyundai Sonata. Every 2021 Sonata Hybrid features a non-turbocharged, 2.0-liter 4-cylinder gasoline engine rated at 150 hp. This engine joins forces with a 39-kilowatt electric motor and a 1.6-kilowatt-hour lithium polymer battery pack. Total system horsepower is 192.

Whereas most hybrids use some type of continuously variable transmission (CVT), the hybrid Sonata uses a specialized 6-speed automatic transmission to manage its gasoline and electric power sources. As a result, the 2021 Sonata Hybrid drives more like a regular Sonata than you might expect.

Equipped with the base 2.5-liter engine, the 2021 Hyundai Sonata SE rates 32 mpg in combined driving. The SEL version lacks the base sedan's start-stop feature (which shuts off the engine when you're stopped in traffic) and rates 31 mpg.

With the 1.6T engine under its hood, the 2021 Sonata has a 30 mpg combined EPA fuel economy rating. The Sonata N Line earns a 27 mpg combined rating.

If fuel efficiency is top priority, the 2021 Hyundai Sonata Hybrid is the way to go. All the hybrid trims earn a 47 mpg EPA fuel economy rating in combined driving.

Most versions of the 2021 Kia K5 have the turbocharged, 1.6-liter 4-cylinder engine as standard. Just like in the Sonata, the 1.6T pumps out 180 hp and 195 pound-feet of torque.

An 8-speed automatic is standard. It drives the K5's front wheels unless you opt for AWD on the LXS or GT-Line.

For more performance, proceed directly to the 2021 Kia K5 GT. The top-of-the-line K5 has the 290-hp, turbocharged, 2.5-liter 4-cylinder engine and 8-speed dual-clutch transmission.

Front-wheel-drive Kia K5s with the 1.6T engine carry either a 31 or 32 mpg fuel economy rating in combined city and highway driving, depending on the trim level (the base LX has start-stop, but higher trims do not). With optional AWD, the K5 LXS and GT-Line rate 29 mpg combined.

Equipped with the larger, more powerful engine, the 2021 Kia K5 GT has a 27 mpg combined EPA rating.

Advantage: Hyundai Sonata

Safety and Driving Assistance

2021 Kia K5 GT Interior Dashboard

2021 Kia K5 GT

The 2021 Hyundai Sonata and 2021 Kia K5 offer similar advanced driving assistance systems (ADAS). They lead the midsize sedan class in this category, but Hyundai and Kia package certain features differently. If you're looking for a specific type of assistance, you'll want to pay attention to exactly what's available on your preferred trim levels.

All Sonatas come with Hyundai SmartSense. This package of ADAS technology includes adaptive cruise control, a forward collision warning system, automatic emergency braking (with both pedestrian and cyclist detection), lane-departure warning, lane-keeping assistance, lane-centering assistance (which Hyundai calls Lane Following Assist), driver attention monitoring, and automatic high-beam headlight control.

Optional on the SEL Plus and standard on both the Sonata Limited and Sonata Hybrid Limited is Highway Driving Assist, a Level 2 semi-autonomous driving assistance system. Although you have to keep your hands on the steering wheel, Highway Driving Assist provides smoother, more refined operation than competitors' offerings in the midsize sedan class.

A blind-spot monitoring system with rear-cross traffic alerts is standard on all Sonatas and Sonata Hybrids, except the base SE trim. On the Limited trims, you also get a blind-spot view monitor (BVM) that projects camera footage of what's in the vehicle’s blind spots within the instrument panel. 

The Limited trims also come with rear automatic emergency braking and a surround-view camera system.

The non-hybrid Sonata Limited comes with a “lite” version of Hyundai's Remote Smart Parking Assist. It's not a true self-parking system, but it allows you to move the car forward and backward while standing outside the vehicle, which might be useful when parking in tight spots.

All 2021 Sonatas have a standard rear-seat reminder system. Most Sonatas also come with Safe Exit Assist, which provides audible warnings to deter occupants from disembarking if the car's blind-spot sensors detect approaching traffic after you've parked. This feature isn't available on the Sonata Hybrid.

The Hyundai Sonata has a 5-star safety rating from the National Highway Traffic Safety Administration (NHTSA) for overall crash protection, though it earned only four stars for front-passenger safety. The Insurance Institute for Highway Safety (IIHS) rates the 2021 Sonata a Top Safety Pick.

The 2021 Kia K5 starts out with a slightly more basic package of ADAS technology. Adaptive cruise control is optional rather than standard. And, while pedestrian detection is standard, you’ll need a more deluxe optional system for cyclist detection and prevention of ill-advised left turns across oncoming traffic.

Otherwise, the K5 has all the standard driving aids included with Hyundai SmartSense. The GT-Line, EX, and GT can all be equipped with Highway Driving Assist as a package option, and it works just as well as it does on the Sonata.

A rear-seat reminder system is standard on all 2021 Kia K5s. Safe Exit Assist is included on all but the base LX. Option packages for the EX and GT contain an enhanced version that keeps the rear doors locked in the event your passengers ignore the Safe Exit Assist warning chime.

The EX trim level has standard rear automatic emergency braking, but this feature is not available on the top-of-the-line GT.

The 2021 Kia K5 earned a 5-star safety rating from the National Highway Traffic Safety Administration (NHTSA) for overall crash protection. It received four stars for front-passenger safety.

The IIHS named the K5 a Top Safety Pick+, the Institute's highest designation for safety.

Advantage: Kia K5

Infotainment and Technology

2021 Hyundai Sonata Limited Silver Rear Quarter

2021 Hyundai Sonata Limited

Hyundai and Kia are also class leaders in the infotainment category. Regardless of which model or trim level you select, you're unlikely to be disappointed in the features or functionality.

The entry-level infotainment interface in the 2021 Hyundai Sonata includes an 8-inch touchscreen display, Android Auto and Apple CarPlay smartphone integration, and two front-seat USB inputs. The audio system has HD radio and six speakers.

A wireless phone charging pad and an additional USB input (in the backseat) are optional on the SEL and standard on the higher trims. You also get a 3-month trial subscription to SiriusXM satellite radio as standard on the SEL. The Sonata Hybrid SEL additionally has a standard, premium Bose audio system with 12 speakers, but this upgrade is limited to higher trims on the regular Sonata.

Hyundai is known for designing user-friendly infotainment interfaces. Indeed, the factory navigation system in the Sonata ranked first among nav systems offered in midsize and large vehicles in the J.D. Power 2020 U.S. Multimedia Quality and Satisfaction Study

The navigation system is optional on the SEL Plus and standard on the Sonata N Line and both Limited trims. It includes a 10.25-inch touchscreen display, subscription-free traffic data, 3 years of complimentary map updates via Blue Link, and the ability to connect two devices simultaneously (one for phone calls, the other for media). The upgraded Bose audio system is also part of the deal.

Most versions of the 2021 Sonata are available with a digital key that uses near field communication (NFC) technology. Notably, it's standard on all hybrid Sonatas.

Hyundai's Digital Key essentially turns your smartphone into the vehicle’s key, allowing you to unlock the doors, start the engine, and drive. It's useful in situations when multiple family members will be driving the car. For now, Digital Key works only with Android phones.

An 8-inch touchscreen infotainment display and wireless Android Auto and Apple CarPlay integration are standard on all versions of the 2021 Kia K5. Also included are two USB ports (front seat), six audio speakers, and HD radio.

Two rear-seat USB inputs and a satellite radio trial subscription are optional on the LXS and standard on the higher trims.

You can get an optional 10.25-inch touchscreen display with factory navigation starting on the GT-Line trim. One downside to the larger screen is that this interface is incompatible with wireless smartphone integration, so you will need to plug in for Apple CarPlay and Android Auto.

A wireless phone charging pad is optional on the GT-Line and standard on higher trims. A 12-speaker Bose audio system is optional on the Kia K5 EX and GT.

Advantage: Neither. Hardware and software are highly similar. The Kia is the obvious pick if wireless smartphone integration is a priority, while only the Hyundai offers digital key capability.

Comfort and Utility

2021 Kia K5 GT Blue Rear Quarter

2021 Kia K5 GT

Entry-level versions of the 2021 Hyundai Sonata come with 6-way manual adjustment (including seat height) for both the driver and front-passenger seats. Other standard amenities include cloth upholstery, manual air-conditioning, and a tilt-and-telescoping steering wheel. 

The Sonata SEL upgrades to an 8-way power-adjustable driver seat (including lumbar) and dual-zone automatic climate control. On the hybrid Sonata, dual-zone climate control is standard on all trim levels, including the base Blue.

The SEL trim also has heated front seats and a smart keyless entry system (key can stay in your pocket or purse) with push-button start. Rear-seat air-conditioning vents are optional on the SEL, and standard on the Sonata Hybrid SEL and all higher trim levels.

You'll find leatherette seat upholstery with simulated suede inserts in the SEL Plus. The N Line has sport seats covered in leather and simulated suede, as well as ambient interior lighting.

The Limited trims feature a 6-way power front-passenger seat, driver memory settings, full leather upholstery, ventilated front seats, and a heated steering wheel. Note that the Sonata Hybrid does not offer seat-height adjustment for its front-passenger seat.

All 2021 Sonatas have a 16 cubic-foot trunk, including the hybrid. A 60/40-split folding rear seat is standard across the board.

Hyundai's hands-free trunk release automatically detects your keyless remote when you're standing behind the midsize sedan and fully opens the trunk. This convenience is standard on the Sonata SEL trim level and on all Sonata Hybrids.

Standard equipment on the 2021 Kia K5 LX includes 6-way manually adjustable front seats (including height adjustment), cloth upholstery, a tilt/telescoping steering wheel, and dual-zone automatic climate control.

A smart keyless system with push-button start is standard on the LXS. And you can get a 10-way power driver seat and heated front seats as options.

The GT-Line comes with cloth and leatherette upholstery, and you can get full leatherette as an option. Other options for the GT-Line include a heated steering wheel and ambient interior lighting.

Standard fare in the EX includes leatherette upholstery, heated and ventilated front seats, and rear-seat air-conditioning vents. A 10-way power front-passenger seat and driver memory settings are optional. 

The Kia K5 GT is equipped similarly, but it has sport seats with extra lateral bolstering and the ventilated seats move to the options list.

You'll find a 16 cubic-foot trunk in every 2021 Kia K5. The base LX has a fixed rear seat that does not fold. All other K5 sedans have 60/40-split folding rear seat. 

Just like on the Hyundai, a smart trunk release detects your remote and automatically opens the trunk lid when you're standing behind the K5. This convenience is standard on all versions, except the LX.

Advantage: Neither. The amenities and space are similar, but the execution and packaging are different. Your preference will depend on your priorities and your test-drive experiences.

Learn More About the Hyundai Sonata and Kia K5

If you’d like to learn more about these midsize sedans, be sure to read our expert reviews of the Hyundai Sonata, including the Sonata Hybrid, and the 2021 Kia K5. To find out how people like you rate vehicles in this segment, be sure to check out our ratings from verified vehicle owners.

Also, please keep in mind that while the information in this article was accurate and valid on April 20, 2021, it may have changed since that date. Always confirm product details and availability with the automaker’s website or your local dealership.

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