The 2021 Kia K5, formerly named the Optima, has a distinct appearance that helps it stand out from the rest of the segment. So, you won’t likely confuse the K5 for a 2021 Hyundai Sonata when passing one on the highway. However, it’s fair to speculate if the Kia K5 is just as Sonata in disguise, as the models share the same platform and powertrain.

Hyundai and Kia’s relationship is quite complicated, as each company owns shares of the other. That’s why it’s no surprise that the 2021 Kia K5 and 2021 Hyundai Sonata offer so many similarities. However, these midsize sedans aren’t carbon copies, and the differences between the two many lead shoppers to prefer one over the other.

What are the key components that make the 2021 Kia K5 a unique vehicle? Let’s take a closer look at this re-branded midsize sedan.

One Korean sedan provides a little more personal space

Getting behind the wheel of a K5 and a Sonata can leave a driver perplexed. The cabins appear to be strikingly similar, but a few differences give each model a unique feel. MotorTrend’s review of the 2021 Kia K5 sheds some light on this issue.

“There was a spell when their products were very different from one another, but after getting out of the Sonata N-Line and into the K5 GT, the lines are increasingly blurred,” said MotorTrend features editor Christian Seabaugh.

The 2021 Kia K5 and Hyundai Sonata are basically the same in terms of space but have a different cockpit setup. MotorTrend noted how the Sonata has an “airy cabin” due to its push-button shifter, which rests next to the cupholders. Meanwhile, the K5’s traditional shift knob has a more cluttered feel, taking up more space between the driver’s seat and the passenger’s seat. 

This could mean a world of difference to buyers who want the most spacious driving experience possible in a midsize sedan.

The 2021 Kia K5 has a simplified engine lineup

Shoppers will notice the 2021 Hyundai Sonata has a different standard engine than the K5. The Sonata S and SE trims are equipped with a 191-hp 2.5-liter four-cylinder engine. Additionally, the Sonata Hybrid is a greener option for eco-conscious drivers. However, those are about the only difference you’ll find in terms of performance, as everything seems to blend together from there.

A 180-hp 1.6-liter turbocharged engine mated to an eight-speed automatic transmission powers the 2021 Kia K5 and the Sonata’s SEL Plus and Limited models. This might seem like a downgrade for Sonata at first, but that’s not quite the case. The 11-hp reduction is offset by a significant boost in torque (181 lb-ft to 195 lb-ft.)

Both vehicles offer performance models – the 2021 Kia K5 GT and the 2021 Hyundai Sonata N Line. These race-inspired sedans make 290 hp and 311 lb-ft of torque by way of a 2.5-liter turbocharged four-cylinder engine.

Should you buy a 2021 Hyundai Sonata or Kia K5?

As with most things in life, many people’s decision will come down to price. These vehicles offer a similar driving experience and feature list. And unless the openness of the Sonata’s cabin is a deciding factor, you might not lean more toward one sedan.

If that’s the case, then the 2021 Kia K5’s lower starting MSRP of $23,490 might hold significant weight. Plus, its engine lineup is less of a headache to sort through. In contrast, the 2021 Hyundai Sonata starts at $23,600, and you’ll need to pay an extra $4,600 in order to get the available 1.6-liter turbocharged four-cylinder engine.

Performance enthusiasts may also be swayed toward Kia’s sedan, considering the Sonata N Line is also pricier than the K5 GT, coming in at $33,200 and $30,490, respectively.