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The SL’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 SL’s 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’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 SL and the 911 have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, crash mitigating brakes, daytime running lights, rearview cameras, available night vision systems and lane departure warning systems.
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 SL’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 SL has a 6300 to 6500 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 SL 450’s standard 3.0 turbo V6 produces 38 lbs.-ft. more torque (369 vs. 331) than the 911’s standard 3.0 turbo 6 cyl. The SL 550’s standard 4.7 turbo V8 produces 6 more horsepower (449 vs. 443) and 126 lbs.-ft. more torque (516 vs. 390) than the 911 S’ standard 3.0 turbo 6 cyl.
On the EPA test cycle the SL 450 gets better fuel mileage than the 911 S Cabriolet RWD Auto 3.0 twin-turbo 6 cyl. (443 HP) (20 city/28 hwy vs. 18 city/23 hwy).
The SL has 2.9 gallons more fuel capacity than the 911’s standard fuel tank (19.8 vs. 16.9 gallons), for longer range between fill-ups. The SL has 2.2 gallons more fuel capacity than the 911 AWD’s standard fuel tank (19.8 vs. 17.6 gallons).
The Mercedes SL 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 SL, 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 SL’s standard front brake rotors are larger than those on the 911:
For better traction, the SL has larger front tires than the 911 (255/35R19 vs. 235/40R19). The SL’s front tires are larger than the largest tires available on the 911 (255/35R19 vs. 245/35R20).
The SL’s 255/35R19 front and 285/30R19 rear tires provide better handling because they have a lower 35 series front and 30 series rear profile (height to width ratio) that provides a stiffer sidewall than the 911’s standard 40 series front and 35 series rear tires.
The SL 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 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’s wheelbase is 5.3 inches longer than on the 911 (101.8 inches vs. 96.5 inches).
For better handling and stability, the track (width between the wheels) on the SL is .3 inches wider in the front and 1.8 inches wider in the rear than the average track on the 911.
For better maneuverability, the SL’s turning circle is .6 feet tighter than the 911’s (36.2 feet vs. 36.8 feet).
The SL’s 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.
The SL has a much larger trunk with its top down than the 911 Cabriolet with its top down (8.5 vs. 4.6 cubic feet). The SL has a much larger trunk with its top up than the 911 Cabriolet with its top up (13.5 vs. 10.4 cubic feet).
With its convertible body style, valet key and remote trunk release lockout, the SL 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 SL’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 SL 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 SL 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’s 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 open on the SL the driver can close them all at the outside door handle or from a distance using the remote (remote must be aimed at door sensor). On a hot day the driver can also lower the windows the same way. 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 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 SL 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.
In poor weather, headlights can lose their effectiveness as grime builds up on their lenses. This can reduce visibility without the driver realizing. The SL has standard headlight washers to keep headlight output high. The 911 doesn’t offer headlight washers.
To shield the driver and front passenger’s vision over a larger portion of the windshield and side windows, the SL has standard extendable sun visors. The 911 doesn’t offer extendable visors.
The SL’s optional Active Parking Assist can parallel park or back into a parking spot by itself. The 911 doesn’t offer an automated parking system.
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