BMW may not be saying much about its upcoming BMW i5, but plenty of other people are.

Though the i5’s nomenclature slots it in between BMW’s battery-electric i3 or plug-in i8, it looks more and more like the i5 will have little in common with its electrified siblings. The latest rumor to start swirling about the upcoming vehicle is that the i5 may be powered by hydrogen.

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Given that BMW has been making waves with the public testing of its fuel cell prototype this summer, it isn’t surprising that some are wondering if this will be the next production powertrain for the company.

But, according to and reported by BMWBlog, this information is coming from German sources with inside information.

Outfitting the i5 with a hydrogen setup also falls in line with recent comments by Matthias Klietz, BMW’s vice president of powertrain research.

SEE ALSO: Mercedes’ and BMW’s Future Emphasizes Fuel Cell Vehicles Over Battery Electric Cars

“A hydrogen fuel-cell vehicle is going to be used for long driving. It can save a lot of power,” said Klietz. “We have categorized it as for a large vehicle, because it will work best if it’s doing long distances – more than 18,000 kilometers [11,185 miles] a year.”

Inside sources also suggest that the i5 won’t be a sedan sized to compete against the upcoming Tesla Model 3. Instead, said BMWBlog, the i5 will be packaged as a crossover, with BMW ditching the vertically-opening doors of the i8 and adding more comfort for passengers.

The release date is predicted to be around 2020, which is on the far end of previous estimates.