2015 Mercedes-Benz S-Class Hybrid review: Electric-drive luxury

Starting at $94,400
  • Engine V6 Cylinder Engine, Turbocharged
  • Drivetrain Rear Wheel Drive
  • MPG 26 MPG
  • Passenger Capacity 5
  • Body Type Sedans

Roadshow Editors' Rating

8.3 Overall
  • Performance 9
  • Features 10
  • Design 7
  • Media 7
Aug 2015

The Good The 2015 Mercedes-Benz S550 Hybrid achieves a remarkably comfortable ride with its air suspension, coddling passengers with a Burmester audio system and massive rear legroom. Its plug-in hybrid drive system can average in the high 20s for fuel economy while good handling dynamics keep it capable through the turns. Driver assistance features handle many of the less interesting tasks of driving.

The Bad Duplicate dial and touchpad controls create confusion in the infotainment interface. Onboard apps are hampered by a data connection that boots up too slowly.

The Bottom Line The 2015 Mercedes-Benz S550 Hybrid adds reasonable fuel economy and a few miles of pure electric driving to an already extraordinarily comfortable, capable and high-tech luxury sedan, brought down only by slow-to-connect onboard data.

Navigating through an urban canyon, skyscrapers to either side, the 2015 Mercedes-Benz S550 Hybrid glides along quietly, its air suspension smoothing the pockmarked pavement and the cabin insulating me from the downtown bustle. I expect these refined qualities from the Mercedes-Benz S-Class, but this one brings additional quiet, as an electric motor drives the wheels, leaving the engine temporarily dormant.

The S550 Hybrid not only brings a full hybrid drivetrain to Mercedes-Benz's flagship S-Class, it adds plug-in capability, letting owners charge its 8.7 kilowatt-hour lithium ion battery pack from the grid.

Unlike the fully electric B-Class , which uses driveline technology from Tesla, the S550 Hybrid's drive system comes from Mercedes-Benz, with a gasoline engine and electric motor mixing power through a seven-speed automatic transmission to the rear wheels. I could select its electric drive mode, but the S550 Hybrid only goes 20 miles on a full charge before the Hybrid drive mode automatically takes over. Still, that 20 miles should be enough to beat London's congestion or sneak into your country home's driveway to catch the help stealing silverware.

2015 Mercedes-Benz S550 Hybrid

The S550 Hybrid uses a gasoline engine and electric motor, mixing power to the rear wheels, to achieve average fuel economy in the high 20s.

Wayne Cunningham/CNET

Remarkably, the S550 Hybrid comes in at the same base price as the standard S550 sedan, $94,400 in the US. With the hybrid, you will sacrifice 13 horsepower, 436 total system output compared with 449 horsepower, and 0.4 second of your zero-to-60 mph time compared with the S550's V-8, but average fuel economy should jump by 5 or 6 mpg, into the high 20s. The S550 Hybrid I drove came with a number of packages, jumping the total price to $117,515 with destination. You won't find anything labeled as an S550 on UK or Australian Mercedes-Benz dealer lots. The UK equivalent is the S500 e L, with a base price of £88,620, while the only S-Class hybrid Mercedes-Benz offers in Australia is the short-wheelbase S300 BlueTec Hybrid.

As with all new S-Class sedans in the US, the S550 Hybrid is a long-wheelbase model, meaning a giraffe's worth of legroom in the rear seats. Add the rear-seat power adjustment, climate control and fluffy headrests, and I would almost prefer to be chauffeured around in this car, except for the fact that it is so interesting to drive.

As with other plug-in hybrids, I could marvel at and partially control the interplay between gasoline engine and electric motor. The virtual tachometer displayed on the big LCD panel showed me when the engine turned off, either at a stop in traffic or when there was enough charge in the battery pack to drive the wheels. I could pull up a power flow animation, showing the mix of power between engine and motor, and whether the battery was collecting energy from braking regeneration.

More directly, I could choose Hybrid, E-mode, E-saver and Charge modes for the hybrid system, and E, E plus or S for the drive modes. Among the former selections, Hybrid mixes gasoline and electric freely, E-mode drives for as long as possible under pure electric power, E-saver preserves the battery charge by relying more on the engine and Charge attempts to add juice to the battery pack with the engine and regenerative braking. Meanwhile, S is for Sport, sharpening throttle and tightening steering, while E and E plus maximize fuel economy. It's a bewildering set of choices, although most drivers will just go with the default Hybrid and E modes.

Three drives

Starting fresh with a full charge, the S550 Hybrid's instrument panel showed 18 miles of estimated electric range, based on how the car had most recently been driven, less than the potential 20 miles. I switched to E-mode for the hybrid system and the E plus drive setting, and took off into San Francisco's heavy urban traffic. The engine remained off as I accelerated from each stoplight, the 85-kilowatt motor proving ample to get moving.

2015 Mercedes-Benz S550 Hybrid

Among its many drive settings, the S550 Hybrid offers differing ways of using the hybrid drive system.

Wayne Cunningham/CNET

The silence of the ride and the smooth acceleration complemented the S550 Hybrid's opulence for a truly sublime experience. To thoroughly enjoy the drive, I turned on my massage seat and played music from my phone through the 13-speaker Burmester audio system. The audio quality was crystal-clear, highlighting each tone and subtle sound from the songs I played. Ever hear the slight cough and intake of breath at the beginning of Pink Floyd's "Wish You Were Here"? Those sounds came through very clearly with this Burmester system.

Tipping the scales at over 5,000 pounds, the S550 Hybrid is a lot of car to move, and I felt that weight each time it gathered momentum, but the electric motor met the challenge. However, those 18 miles proved illusory, as after only 7 actual miles I had burned up 14 miles of potential range. I ascribe that range burn to an adverse environment, with red lights at every intersection and a couple of hills on my route. But those electric miles had a very positive impact on my overall fuel economy.

I took the opposite tack for another drive, taking the S550 Hybrid into the hills, along the same twisty track over which I had tested its non-hybrid sibling, the S550. Choosing Hybrid and Sport for the drive settings, and switching the air suspension to Sport, I abandoned all thought of fuel efficiency. When I hammered the accelerator, the 3-liter V-6, with a turbocharger for each cylinder bank, made an aggressive growl as it reached for its peak 329 horsepower. Aided by the electric motor, there was no hesitation on power delivery and the car built up steam like a freight train.

In the turns, the air suspension proved its worth, fighting the inertial forces attempting to exploit suspension travel. A corner braking system, applying light inside wheel braking, assisted in the turns, making the S550 Hybrid feel shorter than its 17.2 feet. Even with the wheels squealing, it felt manageable and refined.

2015 Mercedes-Benz S550 Hybrid

Despite its size, the S550 Hybrid handles surprisingly well, partly due to its air suspension and corner braking technologies.

Wayne Cunningham/CNET

There is no Sport mode on the stalk drive selector, but the Sport drive mode made shifting from the seven-speed automatic transmission more aggressive. And paddles on the steering wheel let me hold it in third gear for a good set of turns, the virtual tachometer pushing towards the 6,500rpm redline.

Simply cruising down the freeway proved a delight in the big, comfortable S550 Hybrid, especially with adaptive cruise control and lane-keeping assist active. Mercedes-Benz really refined these technologies to a high degree, making them operate smoothly even when other cars cut in front of me.

A relatively new driver assistance feature from Mercedes-Benz, Traffic Jam Assist, proved its mettle as I drove back into San Francisco one afternoon. All freeway ramps into the city showed red, meaning extreme congestion, on the S550 Hybrid's navigation system, its detailed maps displayed on large LCD panel equal to that of the instrument cluster. I took my place in a bumper-to-bumper queue of cars, then turned on adaptive cruise control, setting my speed to 25 mph.

As traffic crept along, the S550 Hybrid kept reasonably close to the car ahead, slowing and starting as needed. Trusting the technology, I took my hands off the wheel and the car steered itself, maintaining its position as it tracked the painted lane lines with its cameras. A couple of times I felt it came too close to the left lane line, but I never had to intervene. Under close supervision, I let it drive itself until I hit surface streets and took over once again.

Mercedes-Benz does not explicitly allow hands-free driving, and at speeds above 20 mph the car would have issued a warning to get my hands back on the wheel.

2015 Mercedes-Benz S550 Hybrid

The S550 Hybrid's head-up display lets you see speed and route guidance while remaining focused on the road.

Wayne Cunningham/CNET

Efficiency and connections

While testing the S550 Hybrid for fuel economy, I made use of all its various drive modes, but I found E plus the most intriguing. As with its E drive mode, E plus enables what Mercedes-Benz refers to as "sailing," decoupling the wheels from the transmission when coasting to conserve momentum. However, E plus makes use of the car's radar to look at traffic ahead and predict when sailing might not be the best strategy. If traffic is slowing ahead, the car engages the transmission to make use of its regenerative braking. I ended up defaulting to E plus, as it in no way interfered with my driving.

Mercedes-Benz posts EPA mileage numbers for the S550 Hybrid of 24 mpg city and 30 mpg highway, suggesting an average in the mid-20s. However, setting out with a full charge on the battery, driving a route that included dreadfully slow traffic in the city, hammering it along a mountain highway, cruising down the freeway and negotiating suburban streets, I achieved a 29 mpg average, an impressive number.

However, before performing the fuel economy test, I noticed the trip computer average dropping below 12 mpg in city driving with no grid charge on the battery. As is the case with all plug-in hybrids I've reviewed, average fuel economy will vary greatly with how frequently you plug it in.

2015 Mercedes-Benz S550 Hybrid

A standard J1772 electric vehicle charging port lets you plug in the S550 Hybrid.

Wayne Cunningham/CNET

To help find places to plug in, Mercedes-Benz includes an app in the S550 Hybrid's infotainment system alongside Google local search, TuneIn and Yelp. This app let me see a list of nearby electric vehicle charging stations, including some basic info on fees and plug types. The S550 Hybrid includes a plug-in port at the rear, so you will want to back into parking spaces, and requires about 2.5 hours for a full charge.

Getting the car's native apps running took quite a bit of patience, as I had to wait a considerable amount of time watching a screen that said "Establishing an Internet connection." This has been a problem with Mercedes-Benz's app connectivity, at least in the US, as the car does not seem to maintain an always-on connection with its mobile network.

Controlling the S550 Hybrid's apps and other infotainment features, such as the stereo and hands-free phone system, is something of a challenge. Mercedes-Benz adds a touchpad hanging over its previous dial controller that accepts gestures and alphanumeric tracing input, amounting to two distinct methods of selecting onscreen content. While I had fun playing with both input methods, it would probably be less distracting if Mercedes-Benz simplified the system. In the plus column, the system was very responsive.

2015 Mercedes-Benz S550 Hybrid

The menu bar format of Mercedes-Benz's COMAND infotainment interface could use refinement.

Wayne Cunningham/CNET

Electric luxury

The current generation of the Mercedes-Benz S-Class is an extraordinarily opulent and comfortable car. The 2015 S550 Hybrid adds the intriguing twist of the plug-in hybrid drivetrain, letting S-Class owners experience fully electric driving. I highly doubt that prospective buyers in this price range penny-pinch over fueling costs, but it can serve as a minor bit of environmental cred compared with the rest of the S-Class lineup. Owners can plug in next to their colleagues' Teslas in the company parking lot.

The wealthy tech geek will get a kick out of the gasoline-electric drive interplay while enjoying one of the most comfortable cars on the road. Mercedes-Benz's driver assist features are at the cutting edge of the industry for production vehicles, due to early research and investment in the technologies.

The big screens making up the instrument panel and infotainment system are impressive, especially when looking at a forest of rendered buildings in an urban area on the navigation system's maps. The infotainment system includes a good set of digital audio sources along with a hands-free phone system, but Mercedes-Benz needs to do some work on this interface, as the touchpad does not complement the dial controller well, instead making up a separate, duplicate control scheme. Internet apps could also be much better integrated within this system, although most drivers won't have the patience for the car to make its data connection.

Tech specs

Model 2015 Mercedes-Benz S550 Hybrid
Power train Turbocharged direct-injection 3-liter V-6 engine, 85-kilowatt electric motor, 7-speed automatic transmission
EPA fuel economy 24 mpg city/30 mpg highway
Observed fuel economy 29 mpg
Navigation Standard with live traffic
Bluetooth phone support Standard
Digital audio sources Internet streaming, Bluetooth streaming, onboard hard drive, iOS integration, USB drive, HD Radio, satellite radio
Audio system Burmester 590-watt 13-speaker system
Driver assistance Head-up display, night vision, surround-view camera, adaptive high-beams, collision warning, pedestrian detection, adaptive cruise control, blind-spot monitor, lane departure prevention
Base price $95,325
Price as tested $117,515

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