The M4 offers an optional Side and Top View Cameras to allow the driver to see objects all around the vehicle on a screen. The C63 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 M4 and the C63 have standard driver and passenger frontal airbags, front side-impact airbags, driver knee airbags, side-impact head airbags, front seatbelt pretensioners, plastic fuel tanks, traction control and electronic stability systems to prevent skidding.
The M4’s corrosion warranty is 8 years and unlimited miles longer than the C63’s (12/unlimited vs. 4/50,000).
BMW pays for scheduled maintenance on the M4 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 C63.
There are over 12 percent more BMW dealers than there are Mercedes dealers, which makes it easier should you ever need service under the M4’s warranty.
The battery on the M4 is in the trunk, which protects it from hot underhood temperatures which can degrade battery life. By keeping the M4’s battery 20 to 30 degrees cooler, its life is increased by years. The C63’s battery is in the hot engine compartment.
In heavy traffic or at stoplights the M4’s engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. The engine is automatically restarted when the driver gets ready to move again. (Start/Stop isn’t accounted in present EPA fuel mileage tests.) The C63 doesn’t offer an automatic engine start/stop system.
The M4 offers optional heat-treated ceramic brake rotors, which last ten to twenty times as long as conventional cast iron rotors, don’t rust, don’t fade during repeated high speed braking, and their lighter weight contribute to better braking, handling and acceleration. The C63 doesn’t offer ceramic brake rotors.
For better traction, the M4 has larger tires than the C63 (F:255/40R18 & R:275/40R18 vs. F:235/40R18 & R:255/35R18).
For a smoother ride and more stable handling, the M4’s wheelbase is 2 inches longer than on the C63 (110.7 inches vs. 108.7 inches).
For better handling and stability, the track (width between the wheels) on the M4 is .4 inches wider in the front and 3.1 inches wider in the rear than on the C63.
The BMW M4 may be more efficient, handle and accelerate better because it weighs about 250 to 300 pounds less than the Mercedes C63.
The M4 Coupe has 2.8 inches more front headroom, .5 inches more front legroom, 1.3 inches more front shoulder room, .6 inches more rear headroom, .7 inches more rear legroom and 1.4 inches more rear shoulder room than the C63 Coupe.
The M4 Coupe has a much larger trunk than the C63 Coupe (15.7 vs. 11.7 cubic feet).
To make loading groceries and cargo easier when your hands are full, the M4’s available trunk can be opened just by kicking your foot under the back bumper, leaving your hands completely free. The C63 doesn’t offer a hands-free gesture to open its trunk, forcing you to put cargo down if your hands are full.
The M4 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 C63 doesn’t offer a heads-up display.
The M4’s rain-sensitive wipers adjust their speed and turn on and off automatically based on the amount of rainfall on the windshield. This allows the driver to concentrate on driving without constantly adjusting the wipers. The C63’s standard manually variable intermittent wipers have to be constantly adjusted.
Heated windshield washer nozzles are standard on the M4 to prevent washer fluid and nozzles from freezing and help continue to keep the windshield clear in sub-freezing temperatures. The C63 doesn’t offer heated windshield washer nozzles.
The M4’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 C63 doesn’t offer an automated parking system.
The 4 Series was chosen as one of Car and Driver’s “Top Ten” in 2014. The C63 has never been a Car and Driver “Top Ten” pick.
The M4 was chosen as one of Automobile Magazine’s “All Stars” for 13 of the last 18 years. The C63 hasn’t been picked since 2009.
The M4 was selected by Automobile Magazine as their 2006 Car of the Year. The C63 has never been chosen.