Hyundai and Kia share far more than a corporate connection. Since Hyundai acquired a 51% stake in Kia after the automaker declared bankruptcy in 1997, the two South Korean brands have shared engines, vehicle architectures, technology, and manufacturing resources.

That means a Hyundai and a Kia may use closely related, or effectively identical, powertrains despite having different styling and cabin designs. The arrangement allows the brands to divide development and manufacturing costs without creating separate supply chains for every model.

Shared Hyundai and Kia engines

One long-running example is the 2.2-liter CRDi turbo-diesel inline-four. It has been offered in the Hyundai Santa Fe and Kia Sorento since 2009, and is also used in vehicles including the Hyundai Palisade and Sonata, as well as the Kia Carnival.

The engine is generally regarded as durable, although piezo-electronic injector problems can cause poor running and potentially expensive repairs. It can also experience high oil consumption, with some examples reportedly using as much as 0.5 liters every 600 miles.

The brands also use the turbocharged 2.0-liter Smartstream inline-four in models such as the Santa Fe, Sonata, and Kia K5. This engine is primarily available in Asian markets. A related turbocharged 2.5-liter Smartstream four-cylinder powers the Hyundai Sonata N Line, Kia Sorento, and several Genesis models. Reports have also suggested that it may be used in future Hyundai N cars, although that application is not confirmed.

Hyundai and Kia share the turbocharged 3.5-liter Smartstream G3.5 V6 as well. Hyundai produces a twin-turbocharged version for Genesis vehicles.

Several shared engines are manufactured in the United States, including the Smartstream G2.5 GDi and T-GDi, G1.6 T-GDi, and G2.0 Atkinson engines. As a result, U.S.-built versions of models such as the Kia Telluride and Sportage, along with the Hyundai Tucson, Santa Cruz, and Santa Fe, may be equipped with engines produced domestically.

Shared engines can also share problems

Engine commonality can simplify manufacturing, but it also means that a defect may affect vehicles from both brands. The 1.8-liter and 2.0-liter Nu inline-fours, along with the 1.8-liter, 2.0-liter, and 2.4-liter Theta II engines, were linked to reports of stalling, seizure, and fires.

Those engines became the subject of recalls and a major class-action lawsuit in the United States. In 2024, Hyundai and Kia agreed to settle the lawsuit by providing cash rebates to eligible owners and extending engine warranties to 15 years or 150,000 miles.

Reportedly affected vehicles included the 2011–2015 Hyundai Sonata Hybrid, 2014–2021 Hyundai Tucson, 2011–2016 Kia Optima Hybrid, and 2011–2013 Kia Sportage, among other models.

Electric vehicles use shared architecture, too

The relationship extends to electric vehicles. The Kia EV6, Hyundai Ioniq 5 and Ioniq 9, and Genesis GV60 use the 800-volt E-GMP architecture, including shared battery packs and electric motors. The Hyundai Ioniq 3 and Kia EV4 use a 400-volt version of the architecture.

Some EVs using these common components have experienced failures involving the Integrated Charging Control Unit, or ICCU. A failure can leave the vehicle unusable. Hyundai and Kia have issued recalls and faced lawsuits related to the issue, while Hyundai has extended warranty coverage for affected models to 15 years or 180,000 miles.

What separates the brands?

Although Hyundai and Kia often share mechanical components, their vehicles do not look or feel identical. Exterior styling and interior layouts are among the primary differences between related models.

For example, shoppers who dislike the current Hyundai Santa Fe’s design may prefer the related Kia Sorento. Similarly, buyers choosing between electric models may favor the Kia EV6’s styling or the retro-inspired appearance of the Hyundai Ioniq 5.