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2014 Mercedes-Benz E550 Cabriolet review: E550's tech eases driving, but apps are useless

The 2014 Mercedes-Benz E550 Cabriolet, with Steering Assist, drives itself in slow traffic while giving passengers a comfortable ride.

Wayne Cunningham Managing Editor / Roadshow
Wayne Cunningham reviews cars and writes about automotive technology for CNET's Roadshow. Prior to the automotive beat, he covered spyware, Web building technologies, and computer hardware. He began covering technology and the Web in 1994 as an editor of The Net magazine.
Wayne Cunningham
10 min read

Cruising down the freeway in the 2014 Mercedes-Benz E550 Cabriolet, I took the opportunity to contemplate the meaning of luxury. The car afforded me plenty of time to ponder, as its adaptive cruise control handled the pedal work and its steering-assist system helped maintain its position in the lane.


2014 Mercedes-Benz E550 Cabriolet

The Good

The <b>2014 Mercedes-Benz E550 Cabriolet's</b> big, turbocharged V-8 gives plenty of power, while the seven-speed transmission and gentle idle-stop feature contribute to fuel economy. Adaptive cruise control combined with the new Steering Assist feature make the car occasionally autonomous.

The Bad

Sport modes only affect the transmission and suspension. The convertible top severely compromises trunk space and the connectivity features are hampered by slow loading.

The Bottom Line

The 2014 Mercedes-Benz E550 Cabriolet is an extraordinarily comfortable car, and offers cutting-edge driver-assistance features, but cabin electronics are in need of some refinement.

Looking at the design and materials surrounding me in the cabin, I noted the significant use of real metal for the vents, buttons, and even some of the speaker grilles. A bright little analog clock sat in the center of the stack, a cue that spoke of tradition. Further evoking tradition was this car's cloth top, a stand against the retractable hard tops that have taken over the industry in recent years.

However, there was technology in this Mercedes-Benz, too. The brilliance of Mercedes-Benz comes in its ability to meld old and new. If you set an LCD TV down next to a Tiffany lamp on an English Oak sideboard, it's going to look haphazard. In the E550 Cabriolet, Mercedes-Benz much more thoughtfully integrated the 7-inch LCD into the dashboard, setting it into a nice frame so that its placement appears natural. Likewise, soft-touch plastics cover the top of the dashboard and doors, a nice-feeling material that doesn't detract from the luxury feel of the car.

2014 Mercedes-Benz E550 Cabriolet defines luxury (pictures)

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Further contributing to the car's elegance was the manner in which the air suspension soaked up the road, and how the the Harman Kardon audio system produced such detailed and balanced music.

But then it dawned on me that at the core of the E550 Cabriolet's luxury were the very systems letting me consider the question. With cruise control on, I didn't have to constantly monitor the speed of the cars in front of me. Mercedes-Benz's Distronic Plus system used its radar to watch what was going on ahead and adjust my speed accordingly.

This system works so well, that when I let it handle the braking while approaching traffic stopped at a light, it settled for a distance from the car ahead which was just about what I would have left. I did have to poke the accelerator to get it going when traffic started moving again. With traffic moving at speed, it tends to leave a couple of car lengths between you and the car ahead, which other drivers will likely grab. No problem though, as Distronic Plus handles sudden changes in traffic very well.

2014 Mercedes-Benz E550 Cabriolet
Mercedes-Benz makes its new Steering Assist feature available on the 2014 E550 Cabriolet. Josh Miller/CNET

Steering Assist, while not completely taking over steering the vehicle, handled minor lane adjustments. At speeds over about 20 mph, I had to keep a hand on the wheel, but I could feel it moving under my grasp as the E550 Cabriolet tracked the car ahead and used cameras to monitor the lane lines. When I became caught in a bit of traffic crawling along at 5 mph, I was able to take my hands off the wheel completely and experience the closest thing to autonomous driving currently in production.

And this was luxury, letting someone or something else handle the drearier details of everyday life, leaving me to enjoy the good parts.

Somewhat refreshed
Mercedes-Benz earned its luxury reputation on big cars such as the E-Class. The E550 Cabriolet, with its power-opening top, adds a little California, or Riviera, fun to the mix.

And while the E550 Cabriolet may share its driveline and many components with the E550 sedan, it actually comes in at half a foot shorter, both in wheelbase and overall length. In its dimensions, the E550 Cabriolet is more akin to the Mercedes-Benz C-Class.

The smaller size does not lead to a sportier look. The current E-Class was launched in 2009, and its sheet metal shows a conservative design. There has been a style refresh during the intervening years; the grille now only has one louver instead of two and the headlight casings encompass the daytime running lights, rather than having them sit apart. The front of the E550 Cabriolet reflects current Mercedes-Benz styling, which evokes a more aggressive feeling.

2014 Mercedes-Benz E550 Cabriolet
The lack of a roofline subtracts style from any convertible, but adds fun, open-top driving. Josh Miller/CNET

As is common with soft tops, that of the E550 Cabriolet lacks any sort of style when it is up. The power operation makes it effortless to open up, and Mercedes-Benz thoughtfully includes a rear windguard so rear-seat passengers won't get overly ruffled. Unfortunately, that top has to go somewhere, so it results in a huge loss of trunk space. Rear cargo volume is a mere 8.8 cubic feet with the top down, and you will want to invest in very flat luggage. Forget about grocery runs for pumpkins, watermelons, or rib roasts.

Dated interface
Tastefully set into the dashboard of the E550 Cabriolet was the 7-inch LCD I mentioned previously, and because of the $3,250 Premium package included on this car, it showed navigation and connected features along with stereo and phone controls. With the jog dial on the console, I could select menus appearing in bands at the top and bottom of the various screens shown on the LCD.

Mercedes-Benz has had this system in play for many years now, but it could due with some usability work. It is not instantly intuitive and even with a lot of experience I still have to dig around the menus to find what I want.

However, I could also control just about any function with the voice command system. It let me enter addresses as a single string, place phone calls by contact name, and select music from a USB drive or iOS device by specific album, artist, or track.

2014 Mercedes-Benz E550 Cabriolet
Mercedes-Benz has been equipping its cars with this COMAND controller for many years now. Josh Miller/CNET

Stored on an onboard hard drive, the E550 Cabriolet's maps show excellent detail, including topographic features for terrain and rendered buildings in metropolitan areas. The route guidance employs rich graphics and clear voice prompts. The system also took into account traffic jams, dynamically changing the route when it found particularly slow traffic ahead. I was amused how it read traffic alerts out loud, and happy I could turn that feature off.

Among the destination entry options was a shortcut to Mercedes-Benz apps, which included Google search and Yelp. I would have liked to see these online destination options better integrated with navigation instead of tucked away in the apps bucket, but the shortcut is convenient. What made these apps basically useless was the lengthy amount of time the car took to load the apps. I suspect Mercedes-Benz did not negotiate an always-on data connection with its provider -- using them is kind of like if you had to reboot your smartphone every time you wanted to launch an app.

Similarly, online music apps were not in the audio sources menu, but tucked away in the app area of Mercedes-Benz's interface. It was clear to me that the available apps were implemented as an addition to the car, instead of Mercedes-Benz taking a more holistic approach to the interface design.

Among the array of broadcast and stored audio sources in the E550 Cabriolet were HD radio and an onboard hard drive, but I was baffled to find a proprietary media port in the console with a 30-pin iOS adapter cable. The inclusion of the proprietary port is relatively new for Mercedes-Benz, and seemed like a step backward from just providing a simple USB port for plugging in an iOS device. There was a USB port in the console, but it did not work with an iOS Lightning cable, and Mercedes-Benz did not include a Lightning cable for its proprietary port. I could have used Apple's Lightning adapter, but I have found the audio quality when using it atrocious.

2014 Mercedes-Benz E550 Cabriolet
HD radio offers clearer audio production and shows more song data than conventional FM. Josh Miller/CNET

Bluetooth audio streaming was the easiest option for any smartphone user. However, the E550 Cabriolet did not have the Bluetooth Host Controller Interface stack, so I had to use my phone to select music.

For other onboard audio sources, I could select music using voice command or through the music library interface on the LCD. Along with the usual lists of artists and albums, I really liked the album cover display, which was a less distracting means of choosing music.

The music I chose, whether played from a CD, over Bluetooth, or from a USB drive, was greatly enhanced by the car's Harman Kardon audio system. With 14 speakers, including a center channel and subwoofer, this system produced music with fine detail. The output was very balanced between bass and treble, offering extended frequency response. A 610-watt amp brought out subtle sounds and instruments from the tracks I fed through this system. The metal grilles on the speakers were also a nice touch.

Gentle power
Under the hood was another sort of amp, this one using two banks of four pumping pistons displacing 4.7 liters. Gasoline was shot into the cylinders through direct injection and twin turbochargers forced air into the mix. The standard V-8 for current 550-designated Mercedes-Benz models, this engine produces 402 horsepower and 443 pound-feet of torque, a walloping amount of power for this 4,000 pound car.

2014 Mercedes-Benz E550 Cabriolet
This turbocharged V-8 has become the standard mill for Mercedes-Benz's bigger cars. Josh Miller/CNET

As is standard with most Mercedes-Benz models these days, that engine was mated to a seven-speed automatic transmission. Lacking a conventional shifter, I had to use a stalk on the steering column to select drive modes. Showing the E-Class' age a bit, the car had a pedal to engage the parking brake rather than an electronic control.

Despite the large engine and power output, the E550 Cabriolet proved surprisingly economical. Its 17 mpg city estimate isn't great, but on the freeway, the trip computer registered an average above the 26 mpg highway rating. Driving in the city took a toll on the fuel economy, but not as much as I would have expected. The E550 Cabriolet's Eco button's sole purpose is to engage the engine's idle-stop feature, shutting down the big V-8 at every stop light.

I wouldn't expect idle-stop to work well with a V-8, but Mercedes-Benz has its system perfected. The engine started quickly and unobtrusively whenever I took my foot off the brake. The same could definitely not be said for the CLA250 I reviewed earlier, even though it had a much smaller engine.

The air suspension and the easily turned steering wheel made the E550 Cabriolet a comfortable and virtually effortless car to drive. The suspension in particular soaked up any rough patches in the road. Although I only took the car on day trips, I imagine it would be very nice for an extended road trip, if you could find someplace to put your luggage.

2014 Mercedes-Benz E550 Cabriolet
An air suspension makes for a very smooth ride. Josh Miller/CNET

The size of the engine might seem a bit much for a medium-sized four-seat convertible, but it was certainly nice to have that power on tap. At idle, the engine burbled quietly with a deep note, giving a hint at what it could do. Under even moderate acceleration, it let loose an enjoyable growl.

Mercedes-Benz has its AMG brand for serious performance cars, leaving the E550 Cabriolet to be a dilettante when it comes to hard driving. Both the transmission and the suspension had sport modes. The buttons for both were plastic and it seemed as if Mercedes-Benz engineers mounted them on the console without much regard for taste or style.

Sport mode for the suspension was palpably different from Comfort. I felt the bumps in the road more and the ride became more rigid, but it didn't degrade to harsh. It dealt with bumps like a well-tuned fixed suspension, damping out any secondary jouncing. In the turns the E550 Cabriolet handled well, its rear-wheel-drive dynamics apparent, but the suspension remained a bit rubbery. The steering boost was unaffected, with the wheel maintaining its light, over-boosted feel.

Putting the transmission into its sport mode made it hold low gears depending on how aggressively I drove -- powering up to a turn and jamming on the brakes made it shift down. It held the low gears for extended periods, even as the tach needle spun up to 6,000.

Mercedes-Benz didn't choose to give the accelerator a sport mode, something I've seen on cars ranging from Mazdas to BMWs. Instead, driving at high revs made the accelerator much more sensitive, with millimeters of travel causing a substantial reaction from the engine.

Ultimately, I wasn't sold on the idea of sport modes for the E550 Cabriolet. I think it would make more sense if Mercedes-Benz had a single button that would not only set the transmission and suspension in sport, but also change the steering and accelerator tuning.

Sometimes autonomous
From both a traditional and a modern standpoint, the 2014 Mercedes-Benz E550 Cabriolet embodies luxury. The engine gives the car an easy power, always ready to do your bidding, while the air suspension delivers about the best automotive ride quality attainable. Surprisingly, fuel economy is not bad either.

Another area where Mercedes-Benz excels is in its driver assistance features. The company pioneered adaptive cruise control, and has now refined it to the point where it works in stop-and-go traffic. Add in Steering Assist, and the car is occasionally autonomous. The car can take over the burden of driving in severe traffic, exactly the sort of situation where you would want a chauffeur.

The audio system makes for another arrow in the luxury quiver, but not all is rosy among the cabin electronics. The navigation system shows maps with a quality to match the car, and the route guidance works very well. The interface to access all these features is dated, however, and could use some refinement. Mercedes-Benz revealed some of its future direction in the new S550, which includes a touchpad for electronics control, but the basic interface remains the same. Likewise, app integration is still an afterthought, and needs a more robust data connection to be really usable.

Tech specs
Model 2014 Mercedes-Benz E550 Cabriolet
Powertrain Turbocharged direct-injection 4.7-liter V-8 engine, seven-speed automatic transmission
EPA fuel economy 17 mpg city/26 mpg highway
Observed fuel economy 23.1 mpg
Navigation Optional, with live traffic
Bluetooth phone support Standard
Digital audio sources Internet streaming, Bluetooth streaming, onboard hard drive, iOS integration, USB drive, satellite radio, HD radio
Audio system Harman Kardon 14-speaker 610-watt system
Driver aids Adaptive cruise control, steering assist, automated parking, lane-departure warning, blind-spot monitor, surround view cameras, rearview camera
Base price $67,300
Price as tested $76,235

2014 Mercedes-Benz E550 Cabriolet

Score Breakdown

Performance 7Features 7Design 6Media 7


Body Type ConvertiblesAvailable Engine GasBody style Convertible