Wireless charging for electric cars is one technology that always seems to be approaching deployment, but hasn't quite gotten there yet.

Several companies make wireless-charging equipment that can be retrofitted to certain vehicles.

And some automakers have included wireless charging on recent concept cars.

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But so far, no manufacturer has offered the feature from the factory.

That may be about to change, however.

The 2017 Mercedes-Benz S 550e plug-in hybrid will soon get a wireless-charging option, Mercedes hybrid powertrain boss Jochen Strenkert told Britain's Auto Express in an interview at the recent Geneva Motor Show.

2016 Mercedes-Benz S550e Plug-In Hybrid

2016 Mercedes-Benz S550e Plug-In Hybrid

This addition will reportedly be part of a refresh of the S-Class plug-in hybrid, which launched in Europe in Fall 2014, but has only been on sale in the U.S. since last July.

Set to debut next year, the refreshed model (S 550e in the U.S., S 500e in Europe) will reportedly boast a greater electric-only range than the current car.

Mercedes expects battery capacity to double every five years, Strenkert said, so it's betting on greater range.

ALSO SEE: 2015 Mercedes-Benz S550e Plug-In Hybrid: Quick Drive (Dec 2015)

The current S550e has an EPA-rated 14 miles of electric range, and gets 58 MPGe combined.

It has an 8.7-kilowatt-hour lithium-ion battery pack, which powers an electric motor integrated with a seven-speed automatic transmission.

The electrified portion of the powertrain works with a 3.0-liter twin-turbocharged gasoline V-6, with total system output pegged at 436 horsepower and 479 pound-feet of torque.

2016 Mercedes-Benz S550e Plug-In Hybrid

2016 Mercedes-Benz S550e Plug-In Hybrid

The S 550e's natural competition remains other big luxury plug-in hybrids, including the Porsche Panamera S E-Hybrid and BMW 740e xDrive.

Wireless charging would give Mercedes a novel feature those competitors don't have.

MORE: 2016 Mercedes-Benz S550 Plug-In Hybrid: First Drive (Sep 2014)

It might also encourage owners to charge more regularly thanks to the added convenience of not having to mess with a charging cord.

And just as the S-Class has served as a herald for other technologies in the past, perhaps it will pave the way for wireless charging to be offered on other, less expensive vehicles.

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