The 911 offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The SL-Class doesn’t offer all-wheel drive.
Both the 911 and the SL-Class 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.
The 911’s corrosion warranty is 6 years and unlimited miles longer than the SL-Class’ (10/unlimited vs. 4/50,000).
J.D. Power and Associates rated the 911 first among midsize premium sporty cars in their 2013 Initial Quality Study. The SL-Class isn’t in the top three.
J.D. Power and Associates’ 2014 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 first in initial quality, above the industry average. With 41 more problems per 100 vehicles, Mercedes is ranked 13th.
As tested in Motor Trend the 911 S is faster than the SL550 (automatics tested):
911 |
SL-Class |
|
Zero to 60 MPH |
3.7 sec |
4.1 sec |
Quarter Mile |
12 sec |
12.5 sec |
Speed in 1/4 Mile |
117.1 MPH |
115.2 MPH |
As tested in Car and Driver the 911 GT3 Coupe is faster than the SL65 AMG (automatics tested):
911 |
SL-Class |
|
Zero to 60 MPH |
3 sec |
3.7 sec |
Zero to 100 MPH |
7.1 sec |
8.1 sec |
5 to 60 MPH Rolling Start |
3.9 sec |
4.2 sec |
Quarter Mile |
11.2 sec |
11.8 sec |
Speed in 1/4 Mile |
126 MPH |
124 MPH |
As tested in Car and Driver the 911 GT3 Coupe is faster than the SL63 AMG (automatics tested):
911 |
SL-Class |
|
Zero to 30 MPH |
1.2 sec |
1.6 sec |
Zero to 60 MPH |
3 sec |
3.6 sec |
Zero to 100 MPH |
7.1 sec |
7.9 sec |
5 to 60 MPH Rolling Start |
3.9 sec |
4.2 sec |
Passing 50 to 70 MPH |
2.1 sec |
2.3 sec |
Quarter Mile |
11.2 sec |
11.8 sec |
Speed in 1/4 Mile |
126 MPH |
124 MPH |
The flat cylinder configuration of the boxer engine in the 911 lowers its center of gravity, enhancing handling stability. The SL-Class doesn’t offer a boxer engine configuration.
On the EPA test cycle the 911 Cabriolet gets better fuel mileage than the SL-Class:
911 |
SL-Class |
|||
RWD |
Base/Manual |
19 city/27 hwy |
n/a |
|
S/Manual |
19 city/27 hwy |
n/a |
||
Base/Auto |
21 city/28 hwy |
20 city/27 hwy |
SL400 |
|
S/Auto |
19 city/27 hwy |
17 city/24 hwy |
SL550 |
|
SL65 AMG |
n/a |
14 city/21 hwy |
||
AWD |
Base/Manual |
19 city/26 hwy |
n/a |
|
S/Manual |
18 city/26 hwy |
n/a |
||
Base/Auto |
20 city/27 hwy |
n/a |
||
S/Auto |
19 city/26 hwy |
n/a |
||
Turbo/Auto |
17 city/24 hwy |
n/a |
||
Turbo S/Auto |
17 city/24 hwy |
n/a |
Regenerative brakes improve the 911’s fuel efficiency by converting inertia back into energy instead of wasting it. The SL-Class doesn’t offer a regenerative braking system.
The 911 GT3’s optional fuel tank has 3.9 gallons more fuel capacity than the SL-Class (23.7 vs. 19.8 gallons).
For better stopping power the 911 Turbo/GT3’s brake rotors are larger than those on the SL-Class:
911 Turbo/GT3 |
911 Turbo/GT3 opt. |
SL550 |
SL63/SL65 |
|
Front Rotors |
15 inches |
16.1 inches |
14.2 inches |
15.8 inches |
Rear Rotors |
15 inches |
15.4 inches |
12.6 inches |
14.2 inches |
The 911 stops much shorter than the SL-Class:
911 |
SL-Class |
||
70 to 0 MPH |
135 feet |
154 feet |
Car and Driver |
60 to 0 MPH |
93 feet |
109 feet |
Motor Trend |
For better ride, handling and brake cooling the 911 has standard 19-inch wheels. Smaller 18-inch wheels are standard on the SL-Class. The 911’s optional 20-inch wheels are larger than the 19-inch front wheels and 20-inch rear wheels optional on the SL-Class.
The 911 offers active sway bars, which help keep it flat and controlled during cornering, but disconnect at lower speeds to smooth the ride. This helps keep the tires glued to the road. The SL-Class doesn’t offer an active sway bar system.
The 911 S Cabriolet handles at 1.03 G’s, while the SL63 AMG pulls only .93 G’s of cornering force in a Car and Driver skidpad test.
The 911 S Cabriolet executes Motor Trend’s “Figure Eight” maneuver 2 seconds quicker than the SL550 (23.7 seconds @ .88 average G’s vs. 25.7 seconds @ .78 average G’s).
For better maneuverability, the 911 Turbo/GT3’s turning circle is 1.4 feet tighter than the SL550’s (34.8 feet vs. 36.2 feet).
The Porsche 911 may be more efficient, handle and accelerate better because it weighs about 750 to 800 pounds less than the Mercedes SL-Class.
The 911 is 4.8 inches shorter than the SL-Class, making the 911 easier to handle, maneuver and park in tight spaces.
The 911 has standard seating for 4 passengers; the SL-Class can only carry 2.
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 SL-Class does not have an oil pressure gauge.
Heated windshield washer nozzles are standard on the 911 to prevent washer fluid and nozzles from freezing and help continue to keep the windshield clear in sub-freezing temperatures. The SL-Class doesn’t offer heated windshield washer nozzles.
On extremely cold Winter days, the 911’s optional heated steering wheel provides comfort, allowing the driver to steer safely and comfortably before the car heater warms up. The SL-Class doesn’t offer a heated steering wheel.
The 911 will cost the buyer less in the long run because of its superior resale value. Kiplinger’s estimates that the 911 will retain a greater percentage of its original price after three and five years than the SL-Class.
911 |
SL-Class |
|
Five Year |
37% to 42% |
28% |
Three Year |
52% to 59% |
48% |
Motor Trend performed a comparison test in its August 2013 issue and the Porsche 911 S Cabriolet won out over the Mercedes SL63 AMG.
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 SL-Class isn’t in the top three.
The 911 was chosen as one of Automobile Magazine’s “All Stars” for 6 of the last 19 years. The SL-Class has never been an “All Star.”
The Porsche 911 outsold the Mercedes SL-Class by over two to one during the 2014 model year.
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