Mercedes S550 Plug-in Hybrid

The 2016 S-Class Plug-in Hybrid now carries a S550 badge.


Critics use these superlatives to describe the style, performance, and comfort of the Mercedes-Benz S-Class: divine, opulent, exquisite and spectacular. The S-Class is widely regarded as one of the finest luxury cars you can buy. The exterior styling—as with every feature inside and out—exudes class and refinement, with sleek lines providing elegance to a large comfortable sedan.

Besides the addition of a charging port—and badging to describe the ability to take on grid-supplied energy—the plug-in version of the S-Class will retain its handsome looks.


The powertrain is comprised of a gas-powered 329-horsepower V-6 engine and an 85-kilowatt electric motor (pulling juice from an 8.7 kilowatt-hour battery)—all integrated with a Mercedes seven-speed automatic transmission. Put that together for 436 horses worth of oomph. Zero-to-60 mph acceleration time is 5.2 seconds, according to Mercedes.

The battery’s pack energy storage, of which 6.4 kWh is usable, means up to 20 miles of all-electric driving if traveling below 87 mph. After those electric miles, the capable V-6 is put to use, with a top speed governed at 130 mph. A haptic kick down-like mechanism on the accelerator pedal helps drivers maintain electric mode, and otherwise drive with maximum efficiency—or consciously decide to push into the pedal for more power.

Four different modes allow drivers to decide to emphasize when to use or save the battery’s energy. Or you can simply allow the computer to make the decision. Those decisions are probably smarter than your own—especially when using the S-50’s navigation system. That’s because the navigation, along with radar guidance, will use data about hills, valleys and other topography to calculate the best mode for optimized performance, energy regenerative and overall efficiency.

Reviewers who drove a pre-production model are divided on handling. Some say the S550 plug-in hybrid handles exactly like the gas version, while others believe the extra 650 pounds makes the car less adept at cornering. While that point is debatable, there’s no doubt that the V-6, even with the electric boost, is not as speedy and smooth as the non-plug S550’s 4.7-liter V8. The same concerns were expressed about the regenerative braking, which to some felt different than traditional brakes. Others, such as Road and Track, say that Mercedes is among the first automakers to “get regenerative brakes done right” and that it’s “natural and almost entirely seamless.”


If you plug in every night, and just let the S550 plug-in hybrid work its magic, you’re likely to break 40 miles per gallon as an average. That’s impressive for a vehicle of the S550s size and capabilities.

But as with every car on the road, efficiency depends on how you drive. And as with other PHEVs, it’s a matter of how often you recharge and how far you commonly drive. Stay within the all-electric range of about 20 miles—and use a feather foot—to achieve mpg numbers on par with many gas hybrids, even the conventional Prius.

However, if you neglect to charge, drive like a demon or cruise for hundreds of miles, the mileage will be more in line with large powerful luxury sedans. And yet, even after the relatively large battery pack is depleted, the vehicle is still a hybrid that can provide a 10 to 20 percent increase in efficiency over more powerful S-Class models.


There’s nothing unusual about the S550’s charging process. If the pack is completely depleted, you can fully replenish it in about two hours from a 240-volt charging station. Or if you choose to use a standard 120-volt outlet, expect a charging time closer to four or five hours. That’s easily accomplished by plugging in every night. Still, it’s nice to be able to come home for a quick pit stop to maintain more all-electric driving—so a home 240-volt charging station is recommended.

The investment in a good home charging setup will come in handy for future possible electric cars with bigger batteries. At some point, you might want an all-electric BMW, Mercedes or Tesla as a garage mate to your plug-in S-Class.

Passenger/Cargo Room

The Mercedes S-Class sits at the top of the list for most luxurious and comfortable interiors. The detailing of the appointments is impressive: diamond-stitched leather, soft touch armrests, footrests for backseat passengers and Alcantara lining on the ceiling.

You’ll have to search hard for faults with the interior of an S-Class. And yet, on the plug-in model, Mercedes engineers use part of the trunk to store the battery pack—thereby its capacity from a cavernous 18.7 cubic feet to a merely decent 13.9 cubes.


Mercedes throws the kitchen-sink of advanced safety features at the S-Class, including the S550 PHEV. We haven’t yet seen the full options list, but expect to see all kinds of sensor-based warning systems, and automated features for keeping lanes, avoiding blind spots, and automatic braking. It’s a showcase for safety.


No pricing yet available, but a conventional S550 starts just below $100,000. Options and enhanced packages will easily send the bottom line to above $130,000.

Comparisons of Similar Cars

The Porsche Panamera S E-hybrid, a luxury sports sedan, has many similarities with the Mercedes S550. Both cars use a 3-liter V6 for gas power. They both offer about 20 miles of all-electric range—although the Porsche’s battery pack is slightly bigger at 9 kWh. The electric motor on the Mercedes is slightly bigger at 85 kW, compared to the Panamera’s 70 kW. As with many comparisons between Mercedes and Porsche vehicles, the S-Class is more about comfortable luxurious cruising, while the Porsche emphasized performance and sportier looks.

Both the Porsche and Mercedes, as plug-in hybrids, offer extensive range from several hundred miles worth of gasoline. Your other option is to go fully electric with Tesla Model S, a full-size sedan with great handling, and available at about the same price, with 265 miles of driving range—plus free road trip fuel via Tesla’s Supercharger network.

Purchase Process

The all-new 2015 S-Class Plug-In Hybrid arrives in California during the second quarter of 2015. Availability in other states will begin in 2016. Expect limited availability and potential waiting lists.

A previous hybrid version of the S-Class (the S400 Hybrid) was produced in limited quantities and discontinued in 2013. In that sense, the S550 Plug-in Hybrid, like its predecessor, could be seen as a production vehicle that tests the technology and market acceptance, as Mercedes works to make a broader portfolio of its vehicles available with plug-in options.

Mercedes S550 Plug-in Hybrid specifications

Availability: Now
Base MSRP: $97000
Est. tax credit: $4700
Technology: Plug-in Hybrid
Body type: Sedan
Seats: 5
EPA Range: 14 miles electric + gasoline
Battery size: 8 kWh
Charging rate: 3.3 kW

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