Certified Benz & Beemer Compares 2012 BMW 6 SERIES VS 2012 Mercedes SL-Class Near Scottsdale, AZ

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2012 Mercedes SL-Class

Safety Comparison

The 6 Series has standard Active Head Restraints, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the Active Head Restraints system moves the headrests forward to prevent neck and spine injuries. The SL-Class doesn’t offer a whiplash protection system.

The 650i offers all wheel drive to maximize traction under poor conditions, especially in ice and snow. The SL-Class doesn’t offer all wheel drive.

A passive infrared night vision system optional on the 6 Series helps the driver to more easily detect people, animals or other objects in front of the vehicle at night. Using an infrared camera to detect heat, the system then displays the image on a monitor in the dashboard. The SL-Class doesn’t offer a night vision system.

The 6 Series’ optional lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane. The SL-Class doesn’t offer a lane departure warning system.

The 6 Series offers an optional Side and Top View Cameras to allow the driver to see objects all around the vehicle on a screen. The SL-Class only offers front and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the sides.

The 6 Series’ 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. The SL-Class doesn’t offer a system to reveal objects in the driver's blind spots.

Compared to metal, the 6 Series’ plastic fuel tank can withstand harder, more intrusive impacts without leaking; this decreases the possibility of fire. The Mercedes SL-Class has a metal gas tank.

Both the 6 Series and the SL-Class 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.

Warranty Comparison

The 6 Series’ corrosion warranty is 8 years and unlimited miles longer than the SL-Class’ (12/unlimited vs. 4/50,000).

BMW pays for scheduled maintenance on the 6 Series for 4 years and 50,000 miles. BMW will pay for oil changes, tire rotation, lubrication and any other scheduled maintenance. Mercedes doesn’t pay scheduled maintenance for the SL-Class.

There are over 12 percent more BMW dealers than there are Mercedes dealers, which makes it easier to get service under the 6 Series’ warranty.

Reliability Comparison

To reliably power the ignition and other systems and to recharge the battery, the 6 Series has a standard 210 amp alternator. The SL-Class’ standard 150 amp alternator and largest (600/63/65) 180 amp alternator aren’t as powerful.

Engine Comparison

The 650i’s standard 4.4 turbo V8 produces 18 more horsepower (400 vs. 382) and 59 lbs.-ft. more torque (450 vs. 391) than the SL550’s standard 5.5 DOHC V8.

As tested in Car and Driver the 650i is faster than the SL550 (automatics tested):

6 Series


Zero to 60 MPH

4.7 sec

4.9 sec

Quarter Mile

13.1 sec

13.5 sec

Speed in 1/4 Mile

110 MPH

106 MPH

For more instantaneous acceleration and better engine flexibility in any gear, the 6 Series’ engines produce their peak torque at lower RPM’s than the SL-Class:


640i 3.0 turbo 6 cyl.

1400 RPM

650i 4.4 turbo V8

1750 RPM

SL550 5.5 DOHC V8

2800 RPM

SL63 AMG 6.2 DOHC V8

5200 RPM

Fuel Economy and Range Comparison

On the EPA test cycle the 640i gets better fuel mileage than the SL550 (21 city/31 hwy vs. 14 city/22 hwy). The 650i RWD gets better fuel mileage than the SL550 (15 city/23 hwy vs. 14 city/22 hwy).

Regenerative brakes improve the 6 Series’ fuel efficiency by converting inertia back into energy instead of wasting it. The SL-Class doesn’t offer a regenerative braking system.

Brakes and Stopping Comparison

The 6 Series’ standard front and rear disc brakes are vented to help dissipate heat for shorter stops with less fading. The rear discs standard on the SL550 are solid, not vented.

The 6 Series stops much shorter than the SL-Class:

6 Series


70 to 0 MPH

167 feet

178 feet

Car and Driver

Tires and Wheels Comparison

For better ride, handling and brake cooling the 6 Series offers optional 20 inch wheels. The SL-Class’ largest wheels are only 19 inches.

Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires standard on the 6 Series can be driven up to 50 miles without any air pressure, allowing you to drive to a service station for a repair. Run-flat tires aren’t available on some tire packages on the SL-Class.

Suspension and Handling Comparison

For a smoother ride and more stable handling, the 6 Series’ wheelbase is 11.6 inches longer than on the SL-Class (112.4 inches vs. 100.8 inches).

For better handling and stability, the track (width between the wheels) on the 6 Series is 1.6 inches wider in the front and 4.7 inches wider in the rear than on the SL-Class.

The 650i Convertible handles at .89 G’s, while the SL550 pulls only .84 G’s of cornering force in a Car and Driver skidpad test.

Chassis Comparison

The 6 Series is 6.8 inches narrower than the SL-Class, making the 6 Series easier to handle and maneuver in traffic.

Passenger Space Comparison

The 6 Series has standard seating for 4 passengers; the SL-Class can only carry 2.

The 6 Series Convertible has 38.5 cubic feet more passenger volume than the SL-Class (89 vs. 50.5).

The 6 Series has 2.6 inches more front headroom and 2.9 inches more front shoulder room than the SL-Class.

Cargo Capacity Comparison

The 6 Series Convertible has a much larger trunk with its top down than the SL-Class with its top down (10.6 vs. 7.2 cubic feet). The 6 Series Convertible has a much larger trunk with its top up than the SL-Class with its top up (12.4 vs. 10.2 cubic feet).

Ergonomics Comparison

The 6 Series offers an optional heads-up display which projects speed and other key instrumentation readouts onto the windshield, allowing drivers to view information without diverting their eyes from the road. The SL-Class doesn’t offer a heads-up display.

The 6 Series’ standard power windows have a locking feature to keep children in the rear seat from operating them. Mercedes does not offer a locking feature on the SL-Class’ standard power windows.

The 6 Series’ front and rear power windows all open or close with one touch of the switches, making it more convenient at drive-up windows and toll booths, or when talking with someone outside of the car. The SL-Class’ rear power window switches have to be held the entire time to close them fully.

While driving with high beams on, sensitive light sensors available for the 6 Series detect other vehicles which could be blinded and automatically switch to low beams. The SL-Class doesn’t offer automatic dimming high beams.

The 6 Series’ standard power mirror controls are mounted on the armrest for easy access. The SL-Class’ standard power mirror controls are on the center console where they can’t be seen without the driver completely removing his eyes from the road.

Optional BMW Apps for the 6 Series allows the driver and passengers access to select programs on their smartphones, including reading text messages aloud, playing internet radio stations, tagging songs to buy them later, following twitter accounts and other online activities without taking their eyes off the road or their hands from the wheel. The SL-Class doesn’t offer factory integrated smartphone program access.

The 6 Series’ optional Parking Assistant can parallel park or back into a parking spot by itself, with the driver only controlling speed with the brake pedal. The SL-Class doesn’t offer an automated parking system.

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