For enhanced safety, the front seat shoulder belts of the Mercedes SL Class are height adjustable to accommodate a wide variety of driver and passenger heights. A better fit can prevent injuries and the increased comfort also encourages passengers to buckle up. The Porsche 911 Cabriolet doesn’t offer height adjustable seat belts.
The SL Class offers optional Parktronic™ to help warn the driver about vehicles, pedestrians or other obstacles behind or in front of their vehicle. The 911 doesn’t offer a front parking aid.
The SL Class has standard Tele Aid, which uses a global positioning satellite (GPS) receiver and a cellular system to get driving directions, remotely unlock your doors if you lock your keys in, help track down your vehicle if it’s stolen or send emergency personnel to the scene if any airbags deploy. The 911 doesn’t offer a GPS response system, only a navigation computer with no live response for emergencies.
Both the SL Class and the 911 have standard driver and passenger frontal airbags, front side-impact airbags, head airbags, front seatbelt pretensioners, four wheel antilock brakes, traction control and electronic stability systems to prevent skidding.
The Mercedes SL Class weighs 494 to 1475 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 55 percent more Mercedes dealers than there are Porsche dealers, which makes it much easier to get service under the SL Class’ warranty.
The SL Class has more powerful engines than the 911:
Horsepower |
Torque |
|
SL550 5.5 DOHC V8 |
382 HP |
391 lbs.-ft. |
SL600 5.5 turbo V12 |
510 HP |
612 lbs.-ft. |
SL63 AMG 6.2 DOHC V8 |
518 HP |
465 lbs.-ft. |
SL65 AMG 6.0 turbo V12 |
604 HP |
738 lbs.-ft. |
911 3.6 DOHC 6 cyl. |
345 HP |
287 lbs.-ft. |
911 S 3.8 DOHC 6 cyl. |
385 HP |
310 lbs.-ft. |
911 GT3 3.6 GT3 6 cyl. |
415 HP |
300 lbs.-ft. |
911 Turbo 3.6 turbo 6 cyl. |
480 HP |
460 lbs.-ft. |
911 GT2 Coupe 3.6 turbo 6 cyl. |
530 HP |
460 lbs.-ft. |
For more instantaneous acceleration and better engine flexibility in any gear, the SL Class’ engines produce their peak horsepower at lower RPM’s than the 911:
Horsepower |
|
SL550 5.5 DOHC V8 |
6000 RPM |
SL600 5.5 turbo V12 |
5000 RPM |
SL63 AMG 6.2 DOHC V8 |
6800 RPM |
SL65 AMG 6.0 turbo V12 |
4800 RPM |
911 3.6 DOHC 6 cyl. |
6500 RPM |
911 S 3.8 DOHC 6 cyl. |
6500 RPM |
911 GT3 3.6 GT3 6 cyl. |
7600 RPM |
911 Turbo 3.6 turbo 6 cyl. |
6000 RPM |
911 GT2 Coupe 3.6 turbo 6 cyl. |
6500 RPM |
An engine control system which can shut down half of the engine’s cylinders helps improve the SL Class V12’s fuel efficiency. The 911 doesn’t offer a system which can shut down part of the engine.
The SL Class has 4.2 gallons more fuel capacity than the 911 RWD’s standard fuel tank (21.1 vs. 16.9 gallons), for longer range between fill-ups.
For better stopping power the SL Class’ brake rotors are larger than those on the 911:
SL550 |
SL Class |
911 |
911 Turbo/GT3/GT2 |
|
Front Rotors |
13.8 inches |
15.4 inches |
12.52 inches |
14.96 inches |
Rear Rotors |
12.6 inches |
14.2 inches |
11.77 inches |
13.78 inches |
For better traction, the SL Class has larger tires than the 911 (F:255/40R18 & R:285/35R18 vs. F:235/40R18 & R:265/40R18). The SL Class’ front tires are larger than the largest tires available on the 911 (255/40R18 vs. 235/35R19).
The SL Class’ standard 285/35R18 rear tires provide better handling because they have a lower 35 series profile (height to width ratio) which provides a stiffer sidewall than the 911’s standard 40 series tires.
Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires available on the SL Class 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 SL Class has a standard space-saver spare tire so you can replace a flat tire and drive to have the flat repaired or replaced. A spare tire isn’t available on the 911, it requires you to depend on roadside assistance and your vehicle will have to be towed.
The SL Class offers an available adjustable active suspension system, which counteracts cornering forces actively, limiting body roll and improving handling and stability. Porsche doesn’t offer an active suspension on the 911.
The SL Class 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 SL Class has vehicle speed sensitive variable-assist power steering, for low-effort parking, better control at highway speeds and during hard cornering, and a better feel of the road. The 911 doesn’t offer variable-assist power steering.
For a smoother ride and more stable handling, the SL Class’ wheelbase is 8.3 inches longer than on the 911 (100.8 inches vs. 92.5 inches).
For better handling and stability, the average track (width between the wheels) on the SL Class is 3 inches wider in the front and .3 inches wider in the rear than the average track on the 911.
The SL Class’ front to rear weight distribution is more even (51% to 49%) than the 911’s (39.1% to 60.9%). This gives the SL Class more stable handling and braking.
The SL65 AMG handles at .93 G’s, while the 911 Cabriolet pulls only .92 G’s of cornering force in a Car and Driver skidpad test.
The SL Class’ standard power retractable hardtop allows a seamless transition from an open car, to a completely sealed coupe. The 911 doesn't offer a retractable hardtop.
With its convertible body style, valet key and remote trunk release lockout, the SL Class offers cargo security. The 911’s non-lockable folding seat and non-lockable remote release defeat cargo security.
Unlike the driver-only memory seat and mirrors optional at extra cost in the 911, the SL Class has standard driver and passenger memory, so that when drivers switch, the memory setting adjusts the driver’s seat, steering wheel position, seatbelt height, outside mirror angle and climate settings and the front passenger seat also adjusts to the new passenger’s preset preferences.
The SL Class’ 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. The 911 doesn’t offer an easy entry system.
If the windows are left down on the SL Class the driver can raise them all using the keyless remote (remote must be aimed at door sensor); on a hot day the driver can lower the windows. The driver of the 911 can’t use the remote to operate the windows.
When the SL Class is put in reverse, the passenger rearview mirror tilts from its original position. This gives the driver a better view of the curb during parallel parking maneuvers. Shifting out of reverse puts the mirror into its original position. The 911’s mirror doesn’t automatically adjust for backing.
The SL Class’ standard dual zone air conditioning allows the driver and front passenger to choose two completely different temperatures so people with different temperature preferences won’t have to compromise. This makes both the driver and front passenger as comfortable as possible. The 911 doesn’t offer dual zone air conditioning.
To keep a safe, consistent following distance, the SL Class offers an optional Distronic, which alters the speed of the vehicle without driver intervention. This allows the driver to use cruise control more safely without constantly having to disengage it when approaching slower traffic. The 911 doesn’t offer an adaptive cruise control.
With optional voice command, the SL Class offers the driver hands free control of the radio and cell phone by simply speaking. The 911 doesn’t offer a voice control system.
Wireless connectivity is standard on the SL Class, connecting the driver and passenger’s cell phones to the vehicle systems. This allows them to use the vehicle’s stereo and hand controls to place calls safely and easily. Porsche doesn’t offer wireless connectivity on the 911.
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