Hyundai and Kia sell hybrids, an electric car, and a hydrogen fuel-cell vehicle in the U.S.--the latter two in limited numbers--but there's one green-car avenue the Korean automakers haven't explored yet.

DON'T MISS: Fewer Gas Stations, But More Diesel Pumps, As Diesel Sales Rise

Both brands offer diesels in other markets, and are now reportedly evaluating whether to bring some of them to the U.S. as well.

The combined Hyundai-Kia is reconsidering diesels for the U.S. as a way to meet stricter efficiency standards, according to a recent report from WardsAuto.

2015 Kia Soul

2015 Kia Soul

Hyundai and Kia reportedly considered selling diesels in the U.S. around five years ago, but backed away because of the anticipated cost of exhaust-aftertreatment systems and the added cost of diesel engines themselves.

It also believed the higher average price of diesel would dissuade customers.

Now, though, officials believe diesel may be necessary to help the carmakers meet U.S. Corporate Average Fuel Economy (CAFE) standards, which mandate a fleet average of 54.5 mpg by 2025. That translates to roughly 42 mpg on the window sticker.

Hyundai and Kia would reportedly launch diesels in the U.S. sometime after 2016, as the CAFE-weighted average rises from 35.5 mpg that year in the final push toward the 54.5 mpg goal.

Diesel probably won't be offered across either brand's entire range, but rather on one or perhaps a handful of models.

2015 Hyundai Tucson

2015 Hyundai Tucson

The company previously considered offering a 3.0-liter diesel V-6 in the now-defunct Hyundai Veracruz and Kia Borrego full-size utility vehicles, but hasn't decided which models would get the new diesel powertrain.

Hyundai and Kia are not the only carmakers with on-again, off-again diesel plans.

RELATED: 2015 Hyundai Tucson Fuel Cell: Hydrogen Crossover First Drive

In the last decade, several automakers--including Honda, Nissan, and Subaru--have considered bringing diesel cars to the U.S. but then dropped those plans.

General Motors did follow through with the Chevrolet Cruze Diesel, which currently makes up a very small percentage of Cruze sales.

Led by the two Korean brands, could round two be more successful?


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