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For enhanced safety, the front and rear seat shoulder belts of the Mercedes S-Class Cabriolet have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision and force limiters to limit the pressure the belts will exert on the passengers. The Porsche 911 doesn’t offer pretensioners for the rear seat belts.
The S-Class Cabriolet’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The 911 doesn’t offer pre-crash pretensioners.
The S-Class Cabriolet has standard front and rear seat side-impact airbags and head airbags, which act as a forgiving barrier between the passengers and the door. Combined with high-strength steel door beams this system increases protection from broadside collisions. The 911 doesn't offer rear-seat side-impact airbags, only ones for front seat occupants.
The S-Class Cabriolet’s blind spot warning system uses digital cameras monitored by computer to alert the driver to moving objects in the vehicle’s blind spots where the side view mirrors don’t reveal them. The 911 doesn’t offer a system to reveal objects in the driver’s blind spots.
To help make backing safer, the S-Class Cabriolet’s cross-path warning system uses wide-angle radar in the rear bumper to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. The 911 doesn’t offer a cross-path warning system.
The S-Class Cabriolet’s driver alert monitor detects an inattentive driver then sounds a warning and suggests a break. According to the NHTSA, drivers who fall asleep cause about 100,000 crashes and 1500 deaths a year. The 911 doesn’t offer a driver alert monitor.
Both the S-Class Cabriolet and the 911 have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, rearview cameras and available night vision systems.
The Mercedes S-Class Cabriolet weighs 1143 to 1430 pounds more than the Porsche 911. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.
There are over 2 times as many Mercedes dealers as there are Porsche dealers, which makes it much easier should you ever need service under the S-Class Cabriolet’s warranty.
The 911’s redline is at 7500 RPM, which causes more engine wear, and a greater chance of a catastrophic engine failure. The S-Class Cabriolet has a 6300 RPM redline.
J.D. Power and Associates’ 2019 Initial Quality Study of new car owners surveyed provide the statistics that show that Mercedes vehicles are better in initial quality than Porsche vehicles. J.D. Power ranks Mercedes 12th in initial quality. With 2 more problems per 100 vehicles, Porsche is ranked 15th.
The S-Class Cabriolet’s 4.0 turbo V8 produces 84 more horsepower (463 vs. 379) and 185 lbs.-ft. more torque (516 vs. 331) than the 911’s standard 3.0 turbo 6-cylinder. The S-Class Cabriolet’s 4.0 turbo V8 produces 20 more horsepower (463 vs. 443) and 126 lbs.-ft. more torque (516 vs. 390) than the 911 S’ standard 3.0 turbo 6-cylinder.
On the EPA test cycle the S 560 Cabriolet gets better fuel mileage than the 911 S Cabriolet RWD Auto (17 city/26 hwy vs. 18 city/23 hwy).
An engine control system that can shut down some of the engine’s cylinders helps improve the S-Class Cabriolet’s fuel efficiency. The 911 doesn’t offer a system that can shut down part of the engine.
The S-Class Cabriolet has 4.2 gallons more fuel capacity than the 911’s standard fuel tank (21.1 vs. 16.9 gallons), for longer range between fill-ups. The S-Class Cabriolet has 3.5 gallons more fuel capacity than the 911 AWD’s standard fuel tank (21.1 vs. 17.6 gallons).
The Mercedes S-Class Cabriolet comes standard with an automatic transmission, for driver comfort, especially in the city. Automatic costs extra on the 911.
A nine-speed automatic is standard on the Mercedes S-Class Cabriolet, for better acceleration and lower engine speed on the highway. Only an eight-speed automatic is available for the 911.
For better stopping power the S-Class Cabriolet’s standard brake rotors are larger than those on the 911:
For better traction, the S-Class Cabriolet has larger front tires than the 911 (245/45R19 vs. 235/40R19).
Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires standard on the S-Class Cabriolet can be driven up to 50 miles without any air pressure, allowing you to drive to a service station for a repair. The 911 doesn’t offer run-flat tires.
The front and rear suspension of the S-Class Cabriolet uses air springs for a smoother, controlled ride than the 911, which uses coil springs. Air springs maintain proper ride height and ride more smoothly.
The S-Class Cabriolet has a standard automatic front and rear load leveling suspension to keep ride height level with a heavy load or when towing. The 911 doesn’t offer a load leveling suspension.
The S-Class Cabriolet’s drift compensation steering can automatically compensate for road conditions which would cause the vehicle to drift from side to side, helping the driver to keep the vehicle straight more easily. The 911 doesn’t offer drift compensation steering.
For a smoother ride and more stable handling, the S-Class Cabriolet’s wheelbase is 19.4 inches longer than on the 911 (115.9 inches vs. 96.5 inches).
For better handling and stability, the track (width between the wheels) on the S-Class Cabriolet is 1.3 inches wider in the front and 3.7 inches wider in the rear than the average track on the 911.
To almost totally eliminate engine vibration in the passenger area, the S-Class Cabriolet has an electronically controlled liquid-filled main engine mount. A computer-controlled electric current in the liquid changes its viscosity, allowing the mount to dampen the engine completely at all RPMs. The 911 uses conventional solid rubber engine mounts.
Because it has more passenger and cargo room, the EPA rates the S-Class Cabriolet a Subcompact car, while the 911 Cabriolet is rated a Minicompact.
The S-Class Cabriolet has 15 cubic feet more passenger volume than the 911 (88 vs. 73).
The S-Class Cabriolet has 6.4 inches more front shoulder room, 5.2 inches more rear headroom, 6.2 inches more rear legroom and 1.6 inches more rear shoulder room than the 911.
The S-Class Cabriolet has a much larger trunk with its top down than the 911 Cabriolet with its top down (6.9 vs. 4.6 cubic feet). The S-Class Cabriolet has a much larger trunk with its top up than the 911 Cabriolet with its top up (12.4 vs. 10.4 cubic feet).
With its convertible body style, valet key and remote trunk release lockout, the S-Class offers cargo security. The 911’s non-lockable folding seat defeats cargo security.
To make loading and unloading groceries and cargo easier when your hands are full, the S-Class Cabriolet’s power trunk can be opened or closed just by kicking your foot under the back bumper, leaving your hands completely free. The 911 doesn’t offer a power or hands-free opening trunk.
The S-Class Cabriolet has a standard remote vehicle starting system, so the vehicle can be started from inside the driver's house. This allows the driver to comfortably warm up the engine before going out to the vehicle. The climate system will also automatically heat or cool the interior. The 911 doesn’t offer a remote starting system.
Unlike the driver-only memory system optional at extra cost in the 911, the S-Class Cabriolet has standard driver and passenger memory, so that when drivers switch, the memory setting adjusts the driver’s seat, steering wheel position and outside mirror angle and the front passenger seat also adjusts to the new passenger’s preset preferences.
The S-Class Cabriolet’s standard easy entry system raises the steering wheel and glides the driver’s seat back, making it easier for the driver to get in and out. An easy entry system costs extra on the 911.
The S-Class Cabriolet offers an optional heads-up display that projects speed and other key instrumentation readouts in front of the driver’s line of sight, allowing drivers to view information without diverting their eyes from the road. The 911 doesn’t offer a heads-up display.
The S-Class Cabriolet’s standard power windows have a locking feature to keep children in the rear seat from operating them, but the driver can still raise and lower all of them with the lock engaged. Porsche does not offer a locking feature on the 911’s standard power windows.
If the windows are left open on the S-Class Cabriolet the driver can close them all at the outside door handle or from a distance using the remote. On a hot day the driver can lower the windows from a distance using the keyless remote. The driver of the 911 can only operate the windows from inside the vehicle, with the ignition on.
In case of a sudden change of weather, the S-Class Cabriolet has a standard remote convertible top that can be raised from a distance to protect the interior of the vehicle from damage. The 911 doesn’t offer a remote top, so the driver will have to run to the car, get in, turn the ignition on and raise the top to prevent the interior from being damaged.
Heated windshield washer fluid is standard on the S-Class Cabriolet to defrost the washer nozzles and quickly clear ice and frost from the windshield without scraping. The 911 doesn’t offer heated windshield washer fluid.
To shield the driver and front passenger’s vision over a larger portion of the windshield and side windows, the S-Class Cabriolet has standard extendable sun visors. The 911 doesn’t offer extendable visors.
A power rear sunshade is standard in the S-Class Cabriolet to help block heat and glare for the rear passengers. The 911 doesn’t offer a rear sunshade.
Both the S-Class Cabriolet and the 911 have standard heated front seats. The S-Class Cabriolet also offers optional heated rear seats to keep those passengers extremely comfortable in the winter. Heated rear seats aren’t available in the 911.
The S-Class Cabriolet has standard massaging front seats in order to maximize comfort and eliminate fatigue on long trips. Massaging seats aren’t available in the 911.
To quickly and conveniently keep personal devices charged without cables tangling and wearing out, the Mercedes S-Class has a standard wireless phone charging system (Qi) in the center console. The 911 doesn’t offer wireless personal charging.
The S-Class Cabriolet has a 115-volt a/c outlet on the center console, allowing you to recharge a laptop or run small household appliances without special adapters that can break or get misplaced. The 911 doesn’t offer a house-current electrical outlet.
The S-Class Cabriolet’s Active Parking Assist can parallel park or back into a parking spot by itself, starting, stopping and changing direction automatically. The 911 doesn’t offer an automated parking system.
The Mercedes S-Class comes in coupe, convertible and sedan bodystyles; the Porsche 911 isn’t available as a sedan.
The Mercedes S-Class outsold the Porsche 911 by 53% during the 2019 model year.
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