2016 Mercedes-Benz S550 Plug-In Hybrid Arriving in U.S. Next Spring

The team at Green Car Reports has driven a prototype of the U.S.-spec car, reporting that is is quiet, luxurious, and likely to carry a six-figure price tag.

And it will be followed within a year by two more plug-in hybrids using the same powertrain: a smaller C-Class sedan, and a refreshed version of the current ML crossover utility vehicle.

The basic powertrain is a gasoline V-6 engine with a single electric motor sandwiched between it and an adapted version of Mercedes’ own seven-speed automatic transmission.

The electric motor can produce 85 kilowatts (114 horsepower) of peak output, and it is powered by a trunk-mounted 8.7-kilowatt-hour lithium-ion battery pack (of which 6.4 kWh is usable).

Total output of the combined powertrain is 325 kW (436 hp), and Mercedes-Benz quotes a 0-to-62-mph acceleration time of 5.2 seconds.

Our initial driving impressions of the new plug-in hybrid S-Class was that the essential qualities of the large luxury sedan have been preserved.

The engine switches off and on all but imperceptibly, and the transitions between power modes are far smoother than in any previous hybrid from Mercedes.

Four driving modes

It’s slightly disconcerting to experienced electric drivers to feel the car’s transmission up- or down-shift while in electric mode, but again, the shifts are so imperceptible that you have to pay close attention to feel it.

There are four basic driving modes: E, for conventional electric-then-hybrid operation, is the default. E+, the ultra-energy-saving mode, is not as annoying in this car as in many less expensive vehicles, and the performance remains tolerable–if not particularly lively.

The E-Save mode allows the driver to conserve battery charge for when it’s needed, turning the car into a conventional hybrid even if the battery has capacity remaining.

And finally, there’s Sport mode, which hustles the big sedan along noticeably more quickly if driven aggressively–but keeps the engine on throughout, with the electric motor providing boost under acceleration.

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