For enhanced safety, the front and rear seat shoulder belts of the Mercedes S-Class have pretensioners to tighten the seatbelts and eliminate dangerous slack in the event of a collision. The BMW 6 Series Gran Coupe doesn’t offer pretensioners for the rear seat belts.
The S-Class’ front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The 6 Series Gran Coupe doesn’t offer pre-crash pretensioners.
For enhanced safety, the front seat shoulder belts of the Mercedes S-Class are height-adjustable to accommodate a wide variety of driver and passenger heights. A better fit can prevent injuries and the increased comfort also encourages passengers to buckle up. The BMW 6 Series Gran Coupe doesn’t offer height-adjustable seat belts.
The S-Class has standard front and rear seat side-impact airbags and head airbags, which act as a forgiving barrier between the passengers and the door. Combined with high-strength steel door beams this system increases protection from broadside collisions. The 6 Series Gran Coupe doesn't offer rear-seat side-impact airbags, only ones for front seat occupants.
The rear seatbelts optional on the S-Class inflate when a collision is detected, helping to spread crash forces over a much larger area of the body and limiting head and neck movement. This can help prevent spinal and internal injuries. The 6 Series Gran Coupe doesn’t offer inflatable seatbelts.
The S-Class offers optional PRE-SAFE Brake, which use forward mounted sensors to warn the driver of a possible collision ahead. If the driver doesn’t react and the system determines a collision is imminent, it automatically applies the brakes at full-force in order to reduce the force of the crash or avoid it altogether. The 6 Series Gran Coupe doesn't offer collision warning or crash mitigation brakes.
To help make backing safer, the S-Class’ optional cross-path warning system uses wide-angle radar in the rear bumper to alert the driver to vehicles approaching from the side, helping the driver avoid collisions. The 6 Series Gran Coupe doesn’t offer a cross-path warning system.
The S-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 6 Series Gran Coupe doesn’t offer a driver alert monitor.
Both the S-Class and the 6 Series Gran Coupe have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, four-wheel antilock brakes, traction control and electronic stability systems to prevent skidding.
J.D. Power and Associates’ 2013 Initial Quality Study of new car owners surveyed provide the statistics that show that Mercedes vehicles are better in initial quality than BMW vehicles. J.D. Power ranks Mercedes 11th in initial quality, above the industry average. With 8 more problems per 100 vehicles, BMW is ranked 18th, below the industry average.
J.D. Power and Associates’ 2013 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Mercedes vehicles are more reliable than BMW vehicles. J.D. Power ranks Mercedes fifth in reliability, above the industry average. With 18 more problems per 100 vehicles, BMW is ranked 16th.
The S-Class has more powerful engines than the 6 Series Gran Coupe:
Horsepower |
Torque |
|
S550 4.7 turbo V8 |
459 HP |
516 lbs.-ft. |
S63 5.5 turbo V8 |
577 HP |
664 lbs.-ft. |
640i Gran Coupe 3.0 turbo 6 cyl. |
315 HP |
330 lbs.-ft. |
650i Gran Coupe 4.4 turbo V8 |
445 HP |
480 lbs.-ft. |
M6 Gran Coupe 4.4 turbo V8 |
560 HP |
500 lbs.-ft. |
M6 Gran Coupe Competition Package 4.4 turbo V8 |
575 HP |
500 lbs.-ft. |
As tested in Car and Driver the S550 is faster than the 640i Gran Coupe (automatics tested):
S-Class |
6 Series Gran Coupe |
|
Zero to 60 MPH |
4.9 sec |
5.6 sec |
Zero to 100 MPH |
11.5 sec |
15.1 sec |
5 to 60 MPH Rolling Start |
5.2 sec |
6.4 sec |
Quarter Mile |
13.4 sec |
14.3 sec |
Speed in 1/4 Mile |
108 MPH |
97 MPH |
The S-Class has 3.4 gallons more fuel capacity than the 6 Series Gran Coupe’s standard fuel tank (21.9 vs. 18.5 gallons), for longer range between fill-ups.
For better stopping power the S-Class’ brake rotors are larger than those on the 6 Series Gran Coupe:
S550 |
S63 |
640i/650i |
M6 w/Carbon Brakes |
|
Front Rotors |
14.6 inches |
16.5 inches |
13.7 inches |
16.1 inches |
Rear Rotors |
14.2 inches |
13.6 inches |
15.6 inches |
For better traction, the S63’s tires are larger than the largest tires available on the 6 Series Gran Coupe (F:255/45R19 & R:285/40R19 vs. F:245/40R19 & R:275/35R19).
The front and rear suspension of the S-Class uses air springs for a smoother, controlled ride than the 6 Series Gran Coupe, which uses coil springs. Air springs maintain proper ride height and ride more smoothly.
The S-Class has a standard automatic front and rear load leveling suspension to keep ride height level with a heavy load or when towing. The S-Class’ height leveling suspension allows the driver to raise ride height for better off-road clearance and then lower it again for easier entering and exiting and better on-road handling. The 6 Series Gran Coupe doesn’t offer a load leveling suspension.
The S-Class’ drift compensation steering can automatically compensate for road conditions which would cause the vehicle to drift from side to side, helping the driver to keep the vehicle straight more easily. The 6 Series Gran Coupe doesn’t offer drift compensation steering.
For a smoother ride and more stable handling, the S-Class’ wheelbase is 7.9 inches longer than on the 6 Series Gran Coupe (124.6 inches vs. 116.7 inches).
The design of the Mercedes S-Class amounts to more than styling. The S-Class has an aerodynamic coefficient of drag of .24 Cd. That is significantly lower than the 6 Series Gran Coupe (.29 to .33) and many sports cars. A more efficient exterior helps keep the interior quieter and helps the S-Class get better fuel mileage.
As tested by Car and Driver while cruising at 70 MPH, the interior of the S550 is quieter than the 640i Gran Coupe (67 vs. 69 dB).
Because it has more passenger and cargo room, the S-Class is rated a Large car by the EPA, while the 6 Series Gran Coupe is rated a Mid-size.
The S-Class has 18 cubic feet more passenger volume than the 6 Series Gran Coupe (115 vs. 97).
The S-Class has 3 inches more front shoulder room, 2.2 inches more rear headroom, 7.7 inches more rear legroom and 4.5 inches more rear shoulder room than the 6 Series Gran Coupe.
For enhanced passenger comfort on long trips the S-Class’ available rear seats recline. The 6 Series Gran Coupe’s rear seats don’t recline.
The S-Class has a much larger trunk than the 6 Series Gran Coupe with its rear seat up (19 vs. 16.2 cubic feet).
To make loading and unloading groceries and cargo easier, especially for short adults or children, the S-Class has a standard power rear 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 6 Series Gran Coupe doesn’t offer a power trunk.
Heated windshield washer fluid is standard on the S-Class to defrost the washer nozzles and quickly clear ice and frost from the windshield without scraping. The 6 Series Gran Coupe doesn’t offer heated windshield washer fluid.
To help keep rear passengers entertained, the S-Class offers optional rear seat controls for the radio which can play a separate audio source. The 6 Series Gran Coupe doesn’t offer rear seat audio controls.
The S-Class has a 115 volt a/c outlet in the center console, allowing you to recharge a laptop or run small household appliances without special adapters which can break or get misplaced. The 6 Series Gran Coupe doesn’t offer a house-current electrical outlet.
The S-Class was chosen as one of Automobile Magazine’s “All Stars” for 3 of the last 14 years. The 6 Series hasn’t been picked since 2005.
The Mercedes S-Class outsold the BMW 6 Series Gran Coupe by 15% during the 2013 model year.
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