Certified Benz & Beemer Compares 2015 Mercedes Benz SL-Class VS 2015 Porsche 911 Near Scottsdale, AZ

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2015 Mercedes Benz SL-Class

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2015 Porsche 911

Safety Comparison

The SL-Class’ 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 SL-Class has standard NECK-PRO Head Restraints, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the NECK-PRO Head Restraints system moves the headrests forward to prevent neck and spine injuries. The 911 doesn’t offer a whiplash protection system.

An active infrared night vision system optional on the SL-Class helps the driver to more easily detect people, animals or other objects in front of the vehicle at night. Using an infrared camera and near-infrared lights to detect heat, the system then displays the image on a monitor in the dashboard. The 911 doesn’t offer a night vision system.

The SL-Class’ optional lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane and gently nudges the vehicle back towards its lane. The 911 doesn’t offer a lane departure warning system.

The SL-Class’ optional 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 and moves the vehicle back into its lane. The 911 doesn’t offer a system to reveal objects in the driver’s blind spots.

The SL-Class’ 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.

The SL-Class has standard mbrace, which uses a global positioning satellite (GPS) receiver and a cellular system to 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, so if you’re involved in an accident and you’re incapacitated help may not come as quickly.

Both the SL-Class and the 911 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 and electronic stability systems to prevent skidding.

Warranty Comparison

There are over 55 percent more Mercedes dealers than there are Porsche dealers, which makes it much easier should you ever need service under the SL-Class’ warranty.

Reliability Comparison

J.D. Power and Associates’ 2014 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Mercedes vehicles are more reliable than Porsche vehicles. J.D. Power ranks Mercedes second in reliability, above the industry average. With 21 more problems per 100 vehicles, Porsche is ranked 9th.

Engine Comparison

The SL-Class has more powerful engines than the 911:



SL400 3.0 turbo V6

329 HP

354 lbs.-ft.

SL550 4.7 turbo V8

429 HP

516 lbs.-ft.

SL63 AMG 5.5 turbo V8

577 HP

664 lbs.-ft.

SL65 AMG 6.0 turbo V12

621 HP

738 lbs.-ft.

911 3.4 DOHC 6 cyl.

350 HP

287 lbs.-ft.

911 S 3.8 DOHC 6 cyl.

400 HP

325 lbs.-ft.

911 GTS 3.8 DOHC 6 cyl.

430 HP

325 lbs.-ft.

911 GT3 Coupe 3.8 DOHC 6 cyl.

475 HP

325 lbs.-ft.

911 Turbo 3.8 turbo 6 cyl.

520 HP

487 lbs.-ft.

As tested in Car and Driver the SL63 AMG is faster than the 911 S (automatics tested):



Zero to 60 MPH

3.6 sec

4 sec

Zero to 100 MPH

7.9 sec

9.3 sec

5 to 60 MPH Rolling Start

4.2 sec

5 sec

Passing 30 to 50 MPH

1.9 sec

2.9 sec

Passing 50 to 70 MPH

2.3 sec

2.9 sec

Quarter Mile

11.8 sec

12.4 sec

Speed in 1/4 Mile

124 MPH

116 MPH

Fuel Economy and Range Comparison

Regardless of its engine, the SL-Class’ engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. (Start/Stop isn’t accounted in present EPA fuel mileage tests.) The 911 GT3 doesn’t offer an automatic engine start/stop system.

The SL-Class has 2.9 gallons more fuel capacity than the 911 RWD/Turbo/GT3’s standard fuel tank (19.8 vs. 16.9 gallons), for longer range between fill-ups.

Brakes and Stopping Comparison

For better stopping power the SL-Class’ standard front brake rotors are larger than those on the 911:



Front Rotors

14.2 inches

13 inches

The SL-Class stops shorter than the 911:



70 to 0 MPH

152 feet

153 feet

Car and Driver

Tires and Wheels Comparison

For better traction, the SL-Class has larger front tires than the 911 (F:255/40R18 & R:285/35R18 vs. F:235/40R19 & R:285/35R19). The SL-Class’ front tires are larger than the largest tires available on the 911 (255/40R18 vs. 245/35R20).

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.

Suspension and Handling Comparison

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 offers an optional 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.

For a smoother ride and more stable handling, the SL-Class’ wheelbase is 5.3 inches longer than on the 911 (101.8 inches vs. 96.5 inches).

For better handling and stability, the average track (width between the wheels) on the SL-Class is 2.9 inches wider in the front and 2.6 inches wider in the rear than the average track on the 911.

The SL-Class’ front to rear weight distribution is more even (50.9% to 49.1%) than the 911’s (39.3% to 60.7%). This gives the SL-Class more stable handling and braking.

The SL63 AMG executes Motor Trend’s “Figure Eight” maneuver quicker than the 911 S Cabriolet (23.9 seconds @ .88 average G’s vs. 24.3 seconds @ .76 average G’s).

Chassis Comparison

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.

As tested by Car and Driver, the interior of the SL63 AMG is quieter than the 911 S Cabriolet:



At idle

49 dB

49 dB


83 dB

91 dB

70 MPH Cruising

68 dB

72 dB

Cargo Capacity Comparison

The SL-Class has a much larger trunk with its top down than the 911 Cabriolet (8.5 vs. 4.8 cubic feet). The SL-Class has a much larger trunk with its top up than the 911 Cabriolet (13.5 vs. 4.8 cubic feet).

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.

To make loading and unloading groceries and cargo easier, especially for short adults or children, the SL-Class offers an optional power trunk, which opens and closes automatically by pressing a button, or optionally by just kicking your foot under the back bumper, completely leaving your hands free. The 911 doesn’t offer a power trunk.

Ergonomics Comparison

Unlike the driver-only memory system 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, 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, making it easier for the driver to get in and out. An easy entry system costs extra on the 911.

If the windows are left down on the SL-Class the driver can raise them all using the key in the outside lock cylinder or 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 only operate the windows from inside the vehicle, with the ignition on.

In case of a sudden change of weather, the SL-Class has a standard remote convertible top which 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.

While driving with high beams on, sensitive light sensors standard on the SL-Class detect other vehicles which could be blinded and automatically switch to low beams. The 911 doesn’t offer automatic dimming high beams.

To shield the driver and front passenger’s vision over a larger portion of the windshield and side windows, the SL-Class has standard extendable sun visors. The 911 doesn’t offer extendable visors.

The SL-Class’ standard air conditioned front seats cool the driver and front passenger and help take the sting out of hot leather in Summer. Air conditioned front seats cost extra on the 911.

The SL-Class’ optional Active Parking Assist can parallel park or back into a parking spot by itself, with the driver only controlling speed with the brake pedal. The 911 doesn’t offer an automated parking system.

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