The Tesla Model S remains the undisputed king of electric cars at the moment primarily because it’s the only real car that is entirely electric. But that will change soon, and BMW will be among those seeking inroads into Tesla’s empire.

BMW’s vector for those inroads will be badged either i5 or i7, and aimed squarely at the Model S, reports Car Magazine.

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Using 5-Series architecture and electric propulsion, the i5/i7/or whatever it will be called should be able to mate proven luxury accommodations, excellent vehicle dynamics, and, if properly executed, a seriously competitive electric drivetrain.

The reported total output of the system is, at the moment, 544 horsepower — more than the Model S P85, but less than the all-wheel-drive, dual-motor P85D’s 691 horsepower.

But the system won’t be all-electric, supposedly. Like the i8, it will carry a four-cylinder gasoline engine to generate power and extend the range beyond its estimated 80 miles of all-electric capacity.

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That, for some, will be a deal breaker—an electric car isn’t supposed to use gasoline, right? Will such a system be enough to take on Tesla? Or will it simply try to carve out another niche?

We likely won’t find out the answer to any of these questions—including the final specification and nature of BMW’s Model S-oriented electric sedan—until sometime after the next 5-Series’ launch in 2018 or thereabouts.