Certified Benz & Beemer Compares 2015 BMW 6 SERIES VS 2015 Mercedes SL-Class Near Scottsdale, AZ

Responsive image


Responsive image

2015 Mercedes SL-Class

Safety Comparison

The 6 Series offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The SL-Class doesn’t offer all-wheel drive.

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 a rear monitor and front and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the sides.

Both the 6 Series 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.

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, lubrication and any other required 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 should you ever need service under the 6 Series’ warranty.

Reliability Comparison

J.D. Power and Associates rated the 6 Series third 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 BMW vehicles are better in initial quality than Mercedes vehicles. J.D. Power ranks BMW 8th in initial quality, above the industry average. With 7 more problems per 100 vehicles, Mercedes is ranked 13th.

Engine Comparison

As tested in Motor Trend the M6 4.4 turbo V8 is faster than the SL550 4.7 turbo V8 (automatics tested):

6 Series


Zero to 60 MPH

3.9 sec

4.1 sec

Quarter Mile

12.3 sec

12.5 sec

Fuel Economy and Range Comparison

On the EPA test cycle the 6 Series gets better fuel mileage than the SL-Class:

6 Series



3.0 turbo 6 cyl./8-spd Auto

20 city/31 hwy

20 city/27 hwy


4.4 twin turbo V8 (445 HP)/8-spd Auto

17 city/25 hwy

17 city/24 hwy

4.7 twin turbo V8/Auto


3.0 turbo 6 cyl./8-spd Auto

20 city/29 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.

The 6 Series M6’s standard fuel tank has 1.3 gallons more fuel capacity than the SL-Class (21.1 vs. 19.8 gallons).

Brakes and Stopping Comparison

For better stopping power the M6 Carbon Brakes’ brake rotors are larger than those on the SL-Class:

M6 Carbon Brakes



Front Rotors

16.1 inches

14.2 inches

15.8 inches

Rear Rotors

15.6 inches

12.6 inches

14.2 inches

The 6 Series stops shorter than the SL-Class:

6 Series


60 to 0 MPH

105 feet

109 feet

Motor Trend

Tires and Wheels Comparison

For better traction, the M6’s tires are larger than the largest tires available on the SL-Class (F:265/40R19 & R:295/35R19 vs. F:255/40R18 & R:285/35R18).

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

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 M6 Convertible’s wheelbase is 10.4 inches longer than on the SL-Class (112.2 inches vs. 101.8 inches).

For better handling and stability, the average track (width between the wheels) on the 6 Series is 1.5 inches wider in the rear than the average track on the SL-Class.

The M6 Convertible handles at .98 G’s, while the SL550 pulls only .94 G’s of cornering force in a Motor Trend skidpad test.

The M6 Convertible executes Motor Trend’s “Figure Eight” maneuver 1.1 seconds quicker than the SL550 (24.6 seconds @ .85 average G’s vs. 25.7 seconds @ .78 average G’s).

Chassis Comparison

As tested by Car and Driver while at idle, the interior of the M6 Convertible is quieter than the SL63 AMG (48 vs. 49 dB).

Passenger Space Comparison

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

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. 8.5 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.

Heated windshield washer nozzles are standard on the 6 Series 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.

A power rear sunshade is optional in the 6 Series Coupe to help block heat and glare for the rear passengers. The SL-Class doesn’t offer a rear sunshade.

On extremely cold Winter days, the 6 Series’ 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.

Economic Advantages Comparison

Insurance will cost less for the 6 Series owner. The Complete Car Cost Guide estimates that insurance for the 6 Series will cost $1470 less than the SL-Class over a five-year period.

The 6 Series will cost the buyer less in the long run because of its superior resale value. Kiplinger’s estimates that the 6 Series will retain 30% to 31% of its original price after five years, while the SL-Class only retains 28%.

Intellichoice estimates that five-year ownership costs (depreciation, financing, insurance, fuel, fees, repairs and maintenance) for the BMW 6 Series will be $33268 to $91746 less than for the Mercedes SL-Class.

Recommendations Comparison

Motor Trend performed a comparison test in its October 2012 issue and they ranked the BMW 650i Convertible higher than the Mercedes SL550.

The BMW 6 Series outsold the Mercedes SL-Class by 80% during the 2014 model year.

© 1991-2016 Advanta-STAR Automotive Research. All rights reserved. Who We Are
Click here to view the disclaimers, limitations and notices about EPA fuel mileage, crash tests, coprights, trademarks, and other issues.