The 6 Series’ pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The C-Class Coupe doesn’t offer pre-crash pretensioners.
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 C-Class Coupe doesn’t offer a night vision 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 C-Class Coupe 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 C-Class Coupe have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, front seatbelt pretensioners, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, front parking sensors, available all wheel drive, crash mitigating brakes, lane departure warning systems and blind spot warning systems.
The 6 Series’ corrosion warranty is 8 years and unlimited miles longer than the C-Class Coupe’s (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 C-Class Coupe.
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.
J.D. Power and Associates’ 2015 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 6th in initial quality, above the industry average. With 12 more problems per 100 vehicles, Mercedes is ranked 14th.
The 6 Series has more powerful engines than the C-Class Coupe:
Horsepower |
Torque |
|
640i 3.0 turbo 6 cyl. |
315 HP |
330 lbs.-ft. |
650i 4.4 turbo V8 |
445 HP |
480 lbs.-ft. |
M6 4.4 turbo V8 |
552 HP |
502 lbs.-ft. |
M6 Competition Package 4.4 turbo V8 |
592 HP |
500 lbs.-ft. |
C250 Coupe 1.8 turbo 4 cyl. |
201 HP |
229 lbs.-ft. |
C350 Coupe 3.5 DOHC V6 |
302 HP |
273 lbs.-ft. |
As tested in Motor Trend the M6 is faster than the C350 Coupe (automatics tested):
6 Series |
C-Class Coupe |
|
Zero to 60 MPH |
3.9 sec |
5.5 sec |
Quarter Mile |
12.3 sec |
14.1 sec |
On the EPA test cycle the 640i gets better fuel mileage than the C350 Coupe:
6 Series |
C-Class Coupe |
|||
RWD |
Auto |
21 city/32 hwy |
20 city/28 hwy |
|
AWD |
Auto |
20 city/29 hwy |
19 city/27 hwy |
Regenerative brakes improve the 6 Series’ fuel efficiency by converting inertia back into energy instead of wasting it. The C-Class Coupe doesn’t offer a regenerative braking system.
Regardless of its engine, the 6 Series’ engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. (Start/Stop isn’t accounted in present EPA fuel mileage tests.) Mercedes only offers an automatic engine start/stop system on the C-Class Coupe C350.
The 6 Series’ standard fuel tank has 1.1 gallons more fuel capacity than the C-Class Coupe (18.5 vs. 17.4 gallons), for longer range between fill-ups. The 6 Series M6’s standard fuel tank has 3.7 gallons more fuel capacity than the C-Class Coupe (21.1 vs. 17.4 gallons).
For better stopping power the 6 Series’ brake rotors are larger than those on the C-Class Coupe:
640i/650i |
M6 Carbon Brakes |
C250 Coupe |
C250 Coupe |
|
Front Rotors |
13.7 inches |
16.1 inches |
11.6 inches |
13.5 inches |
Rear Rotors |
13.6 inches |
15.6 inches |
11.8 inches |
11.8 inches |
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 C250 Coupe are solid, not vented.
The 6 Series stops shorter than the C-Class Coupe:
6 Series |
C-Class Coupe |
||
60 to 0 MPH |
105 feet |
110 feet |
Motor Trend |
For better traction, the 6 Series has larger standard tires than the C-Class Coupe (245/45R18 vs. 225/45R17). The M6’s tires are larger than the largest tires available on the C-Class Coupe (F:265/40R19 & R:295/35R19 vs. F:225/45R17 & R:245/40R17).
The 6 Series’ optional 245/35R20 front and 275/30R20 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 C-Class Coupe’s optional 40 series front and 35 series rear tires.
For better ride, handling and brake cooling the 640i has standard 18-inch wheels. Smaller 17-inch wheels are standard on the C-Class Coupe. The 6 Series’ optional 20-inch wheels are larger than the 18-inch wheels optional on the C-Class Coupe.
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. The C-Class Coupe doesn’t offer run-flat tires.
The 6 Series offers an available active suspension system, which counteracts cornering forces actively, limiting body roll and improving handling and stability. Mercedes doesn’t offer an active suspension on the C-Class Coupe.
For a smoother ride and more stable handling, the M6’s wheelbase is 3.5 inches longer than on the C-Class Coupe (112.2 inches vs. 108.7 inches).
For better handling and stability, the average track (width between the wheels) on the 6 Series is 2.6 inches wider in the front and 3.4 inches wider in the rear than the track on the C-Class Coupe.
The M6 Coupe executes Motor Trend’s “Figure Eight” maneuver 1.8 seconds quicker than the C350 Coupe (24.4 seconds vs. 26.2 seconds).
The 6 Series Coupe has 3 inches more front headroom, .4 inches more front legroom, 6.3 inches more front shoulder room, .2 inches more rear headroom and 2.4 inches more rear shoulder room than the C-Class Coupe.
The 6 Series Coupe has a much larger trunk than the C-Class Coupe (13 vs. 11.7 cubic feet).
The 6 Series offers an optional heads-up display which projects speed and other key instrumentation readouts in front of the driver’s line of sight, allowing drivers to view information without diverting their eyes from the road. The C-Class Coupe 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 C-Class Coupe doesn’t offer heated windshield washer nozzles.
When the 6 Series is put in reverse, the passenger rearview mirror tilts from its original position. This gives the driver a better view of the curb during parallel parking maneuvers. Shifting out of reverse puts the mirror into its original position. The C-Class Coupe’s mirror doesn’t automatically adjust for backing.
Optional air conditioned seats in the 6 Series keep the driver and front passenger comfortable and take the sting out of hot seats in Summer. The C-Class Coupe doesn’t offer air conditioned seats.
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 C-Class Coupe doesn’t offer a heated steering wheel.
The 6 Series (except xDrive)’s 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 C-Class Coupe doesn’t offer an automated parking system.
J.D. Power and Associates rated the 6 Series first among midsize premium sporty cars in owner reported satisfaction. This includes how well the vehicle performs and satisfies its owner’s expectations. The C-Class Coupe isn’t in the top three.
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