The SLC’s optional pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The M4 doesn’t offer pre-crash pretensioners.
The SLC has standard NECK-PRO Head Restraints, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the NECK-PRO Head Restraints system moves the headrests forward to prevent neck and spine injuries. The M4 doesn’t offer a whiplash protection system.
The SLC’s 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 M4 doesn’t offer a driver alert monitor.
Both the SLC and the M4 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, electronic stability systems to prevent skidding, daytime running lights, rearview cameras, available lane departure warning systems, blind spot warning systems and rear parking sensors.
There are over 11 percent more Mercedes dealers than there are BMW dealers, which makes it easier should you ever need service under the SLC’s warranty.
The M4’s redline is at 7600 RPM, which causes more engine wear, and a greater chance of a catastrophic engine failure. The SLC has a 6300 RPM redline.
J.D. Power and Associates’ 2016 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 12th in reliability, above the industry average. With 7 more problems per 100 vehicles, BMW is ranked 14th.
On the EPA test cycle the AMG SLC 43 V6 gets better fuel mileage than the M4 Convertible Auto with its standard turbo 6 cyl. (20 city/29 hwy vs. 16 city/22 hwy).
The SLC AMG’s standard fuel tank has 2.7 gallons more fuel capacity than the M4 (18.5 vs. 15.8 gallons).
For better maneuverability, the SLC’s turning circle is 5.5 feet tighter than the M4’s (34.5 feet vs. 40 feet).
The Mercedes SLC may be more efficient, handle and accelerate better because it weighs about 250 to 600 pounds less than the BMW M4.
The SLC is 1 foot, 9.7 inches shorter than the M4, making the SLC easier to handle, maneuver and park in tight spaces.
The SLC has a standard remote vehicle starting system, so the vehicle can be started from inside the driver's house. This allows the driver to comfortably warm up the engine before going out to the vehicle. The climate system will also automatically heat or cool the interior. The M4 doesn’t offer a remote starting system.
Unlike the driver-only memory system in the M4, the SLC has standard driver and passenger memory, so that when drivers switch, the memory setting adjusts the driver’s seat, steering wheel position and outside mirror angle and the front passenger seat also adjusts to the new passenger’s preset preferences.
The SLC’s standard easy entry system raises the steering wheel, making it easier for the driver to get in and out. The M4 doesn’t offer an easy entry system.
The SLC’s front and rear power windows all lower 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 M4’s rear power window switches have to be held the entire time to open them fully.
To keep a safe, consistent following distance, the SLC offers an optional Distance Pilot DISTRONIC, which alters the speed of the vehicle without driver intervention. This allows the driver to use cruise control more safely without constantly having to disengage it when approaching slower traffic. The M4 doesn’t offer an adaptive cruise control.
Insurance will cost less for the SLC owner. The Complete Car Cost Guide estimates that insurance for the SLC will cost $5925 to $7495 less than the M4 over a five-year period.
IntelliChoice estimates that five-year ownership costs (depreciation, financing, insurance, fuel, fees, repairs and maintenance) for the Mercedes SLC will be $12459 to $14386 less than for the BMW M4.