2019 BMW 4 Series Convertible vs. 2019 Mercedes SLC

Detailed Review, Specifications & Comparison

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Safety

The 4 Series Convertible offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The SLC doesn’t offer all-wheel drive.

The 4 Series Convertible offers an optional Side and Top View Cameras to allow the driver to see objects all around the vehicle on a screen. The SLC 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 4 Series Convertible and the SLC 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 crash mitigating brakes, lane departure warning systems and blind spot warning systems.

The BMW 4 Series Convertible weighs 496 to 1032 pounds more than the Mercedes SLC. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts.

Warranty

The 4 Series Convertible’s corrosion warranty is 7 years longer than the SLC’s (12 vs. 5 years).

BMW pays for scheduled maintenance on the 4 Series Convertible for 3 years and 36,000 miles. BMW will pay for oil changes, lubrication and any other required maintenance. Mercedes doesn’t pay scheduled maintenance for the SLC.

Reliability

J.D. Power and Associates rated the 4 Series Convertible first among compact premium cars in their 2018 Initial Quality Study. The SLC isn’t in the top three in its category.

J.D. Power and Associates’ 2018 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 11th in initial quality, above the industry average. With 5 more problems per 100 vehicles, Mercedes is ranked 14th.

J.D. Power and Associates’ 2018 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that BMW vehicles are more reliable than Mercedes vehicles. J.D. Power ranks BMW 8th in reliability, above the industry average. With 20 more problems per 100 vehicles, Mercedes is ranked 15th.

From surveys of all its subscribers, Consumer Reports’ December 2018 Auto Issue reports that BMW vehicles are more reliable than Mercedes vehicles. Consumer Reports ranks BMW 9 places higher in reliability than Mercedes.

Fuel Economy and Range

On the EPA test cycle the 4 Series Convertible gets better fuel mileage than the SLC:

 

 

 

MPG

4 Series Convertible

 

RWD

430i 2.0 turbo 4 cyl.

24 city/34 hwy

 

 

440i 3.0 turbo 6 cyl.

21 city/29 hwy

 

AWD

430i 2.0 turbo 4 cyl.

22 city/32 hwy

 

 

440i 3.0 turbo 6 cyl.

20 city/29 hwy

SLC

 

RWD

300 2.0 turbo 4 cyl.

23 city/32 hwy

 

 

AMG 43 3.0 turbo V6

20 city/29 hwy

Regenerative brakes improve the 4 Series Convertible’s fuel efficiency by converting inertia back into energy instead of wasting it. The SLC doesn’t offer a regenerative braking system.

Environmental Friendliness

The U.S. Environmental Protection Agency (EPA) certifies the BMW 4 Series Convertible as a “Super Ultra Low Emissions Vehicle” (SULEV). The Mercedes SLC is only certified to “Ultra Low Emissions Vehicle” (ULEV) standards.

Drivetrain

All wheel drive, available in the 4 Series Convertible, provides the best traction for acceleration in wet, dry, and icy conditions. In corners, all wheel drive allows both outside wheels to provide power, balancing the car. This allows for better handling. The Mercedes SLC is not available with all wheel drive.

Brakes and Stopping

For better stopping power the 4 Series Convertible’s standard brake rotors are larger than those on the SLC:

 

4 Series

SLC

Front Rotors

13 inches

12.7 inches

The 4 Series Convertible’s standard front and rear disc brakes are vented to help dissipate heat for shorter stops with less fading. The rear discs standard on the SLC 300 are solid, not vented.

Tires and Wheels

For better ride, handling and brake cooling the 4 Series Convertible has standard 18-inch wheels. Smaller 17-inch wheels are standard on the SLC 300. The 4 Series Convertible’s optional 19-inch wheels are larger than the 18-inch wheels optional on the SLC.

Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires available on the 4 Series Convertible can be driven up to 50 miles without any air pressure, allowing you to drive to a service station for a repair. The SLC doesn’t offer run-flat tires.

Suspension and Handling

For a smoother ride and more stable handling, the 4 Series Convertible’s wheelbase is 14.9 inches longer than on the SLC (110.6 inches vs. 95.7 inches).

For better handling and stability, the track (width between the wheels) on the 4 Series Convertible is 1 inch wider in the rear than the average track on the SLC.

Chassis

The design of the BMW 4 Series Convertible amounts to more than styling. The 4 Series Convertible offers aerodynamic coefficients of drag from .3 to .31 Cd (depending on bodystyle and options). That is lower than the SLC (.33 to .36) and many sports cars. A more efficient exterior helps keep the interior quieter and helps the 4 Series Convertible get better fuel mileage.

Passenger Space

The 4 Series Convertible has standard seating for 4 passengers; the SLC can only carry 2.

The 4 Series Convertible has 41.2 cubic feet more passenger volume than the SLC (90 vs. 48.8).

The 4 Series Convertible has 2.4 inches more front headroom and 3.1 inches more front shoulder room than the SLC.

Cargo Capacity

The 4 Series Convertible has a much larger trunk with its top down than the SLC with its top down (7.8 vs. 6.4 cubic feet). The 4 Series Convertible has a much larger trunk with its top up than the SLC with its top up (13.1 vs. 10.1 cubic feet).

To make loading groceries and cargo easier when your hands are full, the 4 Series Convertible’s available trunk can be opened just by kicking your foot under the back bumper, leaving your hands completely free. The SLC doesn’t offer a hands-free gesture to open its trunk, forcing you to put cargo down if your hands are full.

Ergonomics

The 4 Series Convertible offers an optional heads-up display that 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 SLC doesn’t offer a heads-up display.

The 4 Series Convertible’s front and rear power windows all open or close 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 SLC’s rear power window switches have to be held the entire time to close them fully.

A power rear sunshade is optional in the 4 Series Convertible to help block heat and glare for the rear passengers. The SLC doesn’t offer a rear sunshade.

On extremely cold winter days, the 4 Series Convertible’s optional heated steering wheel provides comfort, allowing the driver to steer safely and comfortably before the car heater warms up. The SLC doesn’t offer a heated steering wheel.

The 4 Series Convertible has a standard dual zone air conditioning allows the driver and front passenger to choose two completely different temperatures so people with different temperature preferences won’t have to compromise. This makes both the driver and front passenger as comfortable as possible. Dual zone air conditioning costs extra on the SLC.

The 4 Series Convertible’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 SLC doesn’t offer an automated parking system.

Model Availability

The BMW 4 Series comes in coupe, convertible and four door hatchback bodystyles; the Mercedes SLC isn’t available as a coupe or four door.

Recommendations

J.D. Power and Associates rated the 4 Series Convertible third among compact premium cars in owner reported satisfaction. This includes how well the vehicle performs and satisfies its owner’s expectations. The SLC isn’t in the top three in its category.

The 4 Series Convertible was chosen as one of Car and Driver’s “Top Ten” in 2014. The SLC has never been a Car and Driver “Top Ten” pick.

The 4 Series Convertible was chosen as one of Automobile Magazine’s “All Stars” in 2014. The SLC has never been an “All Star.”

The BMW 4 Series outsold the Mercedes SLC by almost 16 to one during 2018.

© 1991-2018 Advanta-STAR Automotive Research. All rights reserved.

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