2019 Porsche 911 vs. 2019 Mercedes S-Class Cabriolet

Detailed Review, Specifications & Comparison

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Safety

The 911 has a standard automatic post-collision braking system, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The S-Class Cabriolet doesn’t offer a post collision braking system: in the event of a collision that triggers the airbags, more collisions are possible without the protection of airbags that may have already deployed.

Both the 911 and the S-Class Cabriolet have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, rearview cameras, available all-wheel drive, crash mitigating brakes and blind spot warning systems.

Warranty

The 911’s corrosion warranty is 7 years longer than the S-Class Cabriolet’s (12 vs. 5 years).

Reliability

A reliable vehicle saves its owner time, money and trouble. Nobody wants to be stranded or have to be without a vehicle while it’s being repaired. Consumer Reports rates the 911’s reliability 44 points higher than the S-Class Cabriolet.

J.D. Power and Associates’ 2018 Initial Quality Study of new car owners surveyed provide the statistics that show that Porsche vehicles are better in initial quality than Mercedes vehicles. J.D. Power ranks Porsche fourth in initial quality, above the industry average. With 13 more problems per 100 vehicles, Mercedes is ranked 14th.

J.D. Power and Associates’ 2018 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Porsche vehicles are more reliable than Mercedes vehicles. J.D. Power ranks Porsche second in reliability, above the industry average. With 47 more problems per 100 vehicles, Mercedes is ranked 15th.

From surveys of all its subscribers, Consumer Reports’ December 2018 Auto Issue reports that Porsche vehicles are more reliable than Mercedes vehicles. Consumer Reports ranks Porsche 6 places higher in reliability than Mercedes.

Engine

The 911 GT2 RS’ 3.8 turbo 6 cyl. produces 79 more horsepower (700 vs. 621) than the AMG S 65 Cabriolet’s optional 6.0 turbo V12.

As tested in Car and Driver the 911 S 3.0 turbo 6 cyl. is faster than the AMG S 63 Cabriolet 5.5 turbo V8 (automatics tested):

 

911

S-Class Cabriolet

Zero to 30 MPH

1.2 sec

1.6 sec

Zero to 60 MPH

3.2 sec

3.7 sec

Zero to 100 MPH

7.8 sec

8.7 sec

5 to 60 MPH Rolling Start

4.3 sec

4.5 sec

Passing 50 to 70 MPH

2.6 sec

2.7 sec

Quarter Mile

11.5 sec

12.1 sec

Speed in 1/4 Mile

121 MPH

117 MPH

The flat cylinder configuration of the boxer engine in the 911 lowers its center of gravity, enhancing handling stability. The S-Class Cabriolet doesn’t offer a boxer engine configuration.

Fuel Economy and Range

On the EPA test cycle the 911 gets better fuel mileage than the S-Class Cabriolet:

 

 

911

S-Class Cabriolet

 

RWD

3.0 twin turbo 6 cyl. (370 HP)/7-spd. Manual

20 city/29 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (420 HP)/7-spd. Manual

20 city/28 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (450 HP)/7-spd. Manual

18 city/26 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (420 HP)/7-spd. Auto

22 city/28 hwy

17 city/26 hwy

4.0 turbo V8/Auto

 

3.0 twin turbo 6 cyl. (370 HP)/7-spd. Auto

22 city/28 hwy

14 city/21 hwy

6.0 turbo V12/Auto

 

3.0 twin turbo 6 cyl. (450 HP)/7-spd. Auto

20 city/26 hwy

n/a

 

AWD

3.0 twin turbo 6 cyl. (370 HP)/7-spd Manual

19 city/28 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (420 HP)/7-spd Manual

19 city/28 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (450 HP)/7-spd. Manual

18 city/26 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (420 HP)/7-spd. Auto

21 city/28 hwy

15 city/24 hwy

4.0 turbo V8 /Auto

 

3.0 twin turbo 6 cyl. (370 HP)/7-spd. Auto

21 city/28 hwy

n/a

 

 

3.0 twin turbo 6 cyl. (450 HP)/7-spd. Auto

20 city/25 hwy

n/a

 

 

3.8 twin turbo 6 cyl. (540 HP)/7-spd. Auto

19 city/24 hwy

n/a

 

 

3.8 twin turbo 6 cyl. (580 HP)/7-spd. Auto

19 city/24 hwy

n/a

 

Regenerative brakes improve the 911’s fuel efficiency by converting inertia back into energy instead of wasting it. The S-Class Cabriolet doesn’t offer a regenerative braking system.

The 911 GT2 RS’ optional fuel tank has 2.6 gallons more fuel capacity than the S-Class Cabriolet (23.7 vs. 21.1 gallons).

Transmission

The 911 offers a manual transmission for better acceleration, control and fuel economy. The S-Class Cabriolet doesn’t offer a manual transmission.

The 911 offers an optional sequential manual gearbox (SMG). With no clutch pedal to worry about and a fully automatic mode, an SMG is much more efficient than a conventional automatic but just as easy to drive. The S-Class Cabriolet doesn’t offer an SMG.

Brakes and Stopping

The 911 stops much shorter than the S-Class Cabriolet:

 

911

S-Class Cabriolet

 

70 to 0 MPH

139 feet

168 feet

Car and Driver

Tires and Wheels

For better traction, the 911 GT2 RS/GT3 RS’ tires are larger than the largest tires available on the S-Class Cabriolet (F:265/35R20 & R:325/30R21 vs. F:255/40R20 & R:285/35R20).

The 911’s standard 235/40R19 front and 295/35R19 rear tires provide better handling because they have a lower 40 series front and 35 series rear profile (height to width ratio) that provides a stiffer sidewall than the S 560 Cabriolet’s standard 45 series front and 40 series rear tires. The 911’s optional 245/35R20 front and 305/30R20 rear tires have a lower 35 series front and 30 series rear profile than the S-Class Cabriolet’s optional 40 series front and 35 series rear tires.

For better ride, handling and brake cooling the 911 GT2 RS/GT3 RS has standard 21-inch rear wheels. The S-Class Cabriolet’s largest wheels are only 20-inches.

Suspension and Handling

The 911 offers active sway bars, which help keep it flat and controlled during cornering, but disconnect at lower speeds to smooth the ride and offer greater off-road suspension articulation. This helps keep the tires glued to the road on-road and off. The S-Class Cabriolet doesn’t offer an active sway bar system.

For better maneuverability, the 911 GT2 RS’ turning circle is 4.4 feet tighter than the S 560 Cabriolet’s (33.6 feet vs. 38 feet). The 911’s turning circle is 2.6 feet tighter than the S63/65 AMG Cabriolet’s (36.4 feet vs. 39 feet).

Chassis

The Porsche 911 may be more efficient, handle and accelerate better because it weighs about 1300 to 1700 pounds less than the Mercedes S-Class Cabriolet.

The 911 is 1 foot, 9 inches shorter than the S-Class Cabriolet, making the 911 easier to handle, maneuver and park in tight spaces.

The front grille of the 911 uses electronically controlled shutters to close off airflow and reduce drag when less engine cooling is needed. This helps improve highway fuel economy. The S-Class Cabriolet doesn’t offer active grille shutters.

Cargo Capacity

The 911’s standard rear seats fold to accommodate long and bulky cargo. The S-Class Cabriolet doesn’t offer folding rear seats, only a ski pass-through.

Servicing Ease

J.D. Power and Associates surveys of service recipients show that Porsche service is better than Mercedes. J.D. Power ranks Porsche second in service department satisfaction. With a 6% lower rating, Mercedes is ranked 6th.

Ergonomics

The 911’s instruments include an oil pressure gauge and a temperature gauge – which could save your engine! Often ‘idiot lights’ don’t warn you until damage has been done. The S-Class Cabriolet does not have an oil pressure gauge.

In poor weather, headlights can lose their effectiveness as grime builds up on their lenses. This can reduce visibility without the driver realizing. The 911 offers available headlight washers to keep headlight output high. The S-Class Cabriolet doesn’t offer headlight washers.

Recommendations

Consumer Reports® recommends both the Porsche 911 and the Mercedes S-Class Cabriolet, based on reliability, safety and performance.

J.D. Power and Associates rated the 911 first among midsize premium sporty cars in owner reported satisfaction. This includes how well the vehicle performs and satisfies its owner’s expectations. The S-Class Cabriolet isn’t in the top three.

The 911 Carrera GTS was chosen as one of Automobile Magazine’s “All Stars” in 2018. The S-Class Cabriolet has never been an “All Star.”

© 1991-2018 Advanta-STAR Automotive Research. All rights reserved.

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