Subaru, to which auto writers often attach the adjective "quirky," has been a quiet success story in the U.S. market, which now provides almost half its global sales.

The company's crossover utility vehicles handle more like cars than those from other makers, and its sedans and hatchbacks are set apart by standard all-wheel drive.

Still, it's just one-tenth the size of giants GM, Toyota, or Volkswagen, meaning that meeting tough upcoming regulations will be a challenge purely for the cost involved.

DON'T MISS: Subaru Impreza 5-Door Concept: Tokyo Motor Show Live Photos & Video

The company is one of the "intermediate" carmakers that will be subject to California zero-emission vehicle requirements starting in the 2018 model year.

It plans to meet them by launching a plug-in hybrid vehicle that has yet to be unveiled, though it's possible that will be sold only in the states that have adopted California's emission rules.

Its sole electrified vehicle thus far is the low-volume Subaru Crosstrek Hybrid, a mild-hybrid variant of its wildly popular compact crossover hatchback.

2014 Subaru XV Crosstrek Hybrid - Quick Drive, July 2014

2014 Subaru XV Crosstrek Hybrid - Quick Drive, July 2014

Now comes a report from Japan, however, that Subaru will launch an all-electric crossover utility vehicle in 2021—though the company declined to confirm that report.

The vehicle was first mentioned in an article published on August 8 by Japan's Nikkan Kogyo Shimbun newspaper, according to U.S. industry trade journal Automotive News.

The all-electric crossover would be based on a future generation of the company's Forester compact crossover or Outback mid-size utility vehicle, it suggested.

ALSO SEE: Subaru Viziv Future Concept Previews Next-Generation Hybrid System

Both vehicles will, by then, have moved to the flexible Subaru Global Architecture unveiled earlier this year, which will underpin all future Subaru vehicles.

That component set is designed to accommodate not only the company's flat-four engines and all-wheel-drive systems, but also hybrids, plug-in hybrids, and full electric vehicles.

The first vehicle to use the new architecture will be the 2017 Subaru Impreza, unveiled earlier this year.

2017 Subaru Impreza 5-Door, 2016 New York Auto Show

2017 Subaru Impreza 5-Door, 2016 New York Auto Show

That model will go into production for North America at Subaru's Indiana assembly plant later this year, joining the Outbacks and Legacies built there since 1989.

Supplies of the Impreza, and especially the more profitable Crosstrek based on it, have been constrained by capacity in Japan; North American production is intended to solve that.

The 2017 Impreza will be followed a year later by the new Impreza-based 2018 Subaru Crosstrek, and then by a new Forester crossover for the 2019 model year.

CHECK OUT: Who Killed the Electric Car? Subaru To Slay Plug-In Stella EV (Jan 2011)

Finally, 2020 will see new versions of the Legacy sedan and Outback wagon, completing the company's transition of its North American products to the new architecture.

That would coordinate nicely with the idea that either the Forester or the Outback would serve as the basis for the all-electric SUV.

Dominick Infante of Subaru's U.S. arm declined to comment on the report.

2017 Subaru Outback

2017 Subaru Outback

An electric crossover would actually return Subaru to a vehicle type it abandoned more than six years ago, when it took the Japan-only all-electric Stella EV minicar out of production.

The all-electric three-door minicar, only offered in Japan, never sold anywhere near as well as its contemporary the five-door Mitsubishi i-MiEV.

With luck, perhaps an all-electric crossover utility vehicle will do better among Subaru's often progressive, active-sports, and outdoorsy buyers.


Follow GreenCarReports on Facebook and Twitter.