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The C-Class Cabriolet’s pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The MX-5 Miata doesn’t offer pre-crash pretensioners.
The C-Class Cabriolet offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The MX-5 Miata doesn’t offer all-wheel drive.
The C-Class Cabriolet offers an optional Surround View System to allow the driver to see objects all around the vehicle on a screen. The MX-5 Miata only offers a rear monitor.
The C-Class Cabriolet’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 MX-5 Miata doesn’t offer a driver alert monitor.
Both the C-Class Cabriolet and the MX-5 Miata have standard driver and passenger frontal airbags, front side-impact 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 and rear cross-path warning.
The Mercedes C-Class Cabriolet weighs 1376 to 1673 pounds more than the Mazda MX-5 Miata. The NHTSA advises that heavier cars are much safer in collisions than their significantly lighter counterparts. Crosswinds also affect lighter cars more.
The C-Class Cabriolet comes with a full 4-year/50,000-mile basic warranty, which covers the entire car and includes 24-hour roadside assistance. The MX-5 Miata’s 3-year/36,000-mile basic warranty expires 1 year and 14,000 miles sooner.
The MX-5 Miata’s redline is at 7500 RPM, which causes more engine wear, and a greater chance of a catastrophic engine failure. The C-Class Cabriolet has a 6500 RPM redline.
J.D. Power and Associates’ 2019 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Mercedes vehicles are more reliable than Mazda vehicles. J.D. Power ranks Mercedes 13th in reliability, above the industry average. With 25 more problems per 100 vehicles, Mazda is ranked 21st.
The C-Class Cabriolet’s 2.0 turbo 4-cylinder produces 74 more horsepower (255 vs. 181) and 122 lbs.-ft. more torque (273 vs. 151) than the MX-5 Miata’s 2.0 DOHC 4-cylinder.
In heavy traffic or at stoplights the C-Class Cabriolet’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 MX-5 Miata doesn’t offer an automatic engine start/stop system.
The C-Class Cabriolet has 5.5 gallons more fuel capacity than the MX-5 Miata (17.4 vs. 11.9 gallons), for longer range between fill-ups.
In its Green Vehicle Guide, the U.S. Environmental Protection Agency (EPA) rates the Mercedes C-Class Cabriolet higher (6 out of 10) than the Mazda MX-5 Miata (3). This means the C-Class Cabriolet produces up to 23.4 pounds less smog-producing pollutants than the MX-5 Miata every 15,000 miles.
The Mercedes C-Class Cabriolet comes standard with an automatic transmission, for driver comfort, especially in the city. Automatic costs extra on the MX-5 Miata.
A nine-speed automatic is standard on the Mercedes C-Class Cabriolet, for better acceleration and lower engine speed on the highway. Only a six-speed automatic is available for the MX-5 Miata.
All wheel drive, available in the C-Class Cabriolet, 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 Mazda MX-5 Miata is not available with all wheel drive.
For better stopping power the C-Class Cabriolet’s brake rotors are larger than those on the MX-5 Miata:
The C-Class Cabriolet’s standard front and rear disc brakes are vented to help dissipate heat for shorter stops with less fading. The rear discs on the MX-5 Miata are solid, not vented.
The C-Class Cabriolet stops much shorter than the MX-5 Miata:
70 to 0 MPH
Car and Driver
For better traction, the C-Class Cabriolet has larger tires than the MX-5 Miata (F:225/45R18 & R:245/40R18 vs. 195/50R16). The C-Class Cabriolet’s tires are larger than the largest tires available on the MX-5 Miata (F:225/45R18 & R:245/40R18 vs. 205/45R17).
The C-Class Cabriolet’s standard 225/45R18 front and 245/40R18 rear tires provide better handling because they have a lower 45 series front and 40 series rear profile (height to width ratio) that provides a stiffer sidewall than the MX-5 Miata Sport’s standard 50 series tires. The AMG C 43 Cabriolet’s optional 225/40R19 front and 245/35R19 rear tires have a lower 40 series front and 35 series rear profile than the MX-5 Miata Club/Grand Touring’s 45 series tires.
For better ride, handling and brake cooling the C-Class Cabriolet has standard 18-inch wheels. Smaller 16-inch wheels are standard on the MX-5 Miata Sport. The AMG C 43 Cabriolet’s optional 19-inch wheels are larger than the 17-inch wheels on the MX-5 Miata Club/Grand Touring.
The Mercedes C-Class Cabriolet’s wheels have 5 lugs for longer wheel bearing life, less chance of rotor warping and greater strength. The Mazda MX-5 Miata only has 4 wheel lugs per wheel.
Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires standard on the C-Class Cabriolet can be driven up to 50 miles without any air pressure, allowing you to drive to a service station for a repair. The MX-5 Miata doesn’t offer run-flat tires.
The C-Class Cabriolet offers an optional space-saver spare tire so you can replace a flat tire and drive to have the flat repaired or replaced. A spare tire isn’t available on the MX-5 Miata, it requires you to depend on roadside assistance and your vehicle will have to be towed.
The C-Class Cabriolet has vehicle speed sensitive variable-assist power steering, for low-effort parking, better control at highway speeds and during hard cornering, and a better feel of the road. The MX-5 Miata doesn’t offer variable-assist power steering.
The C-Class Cabriolet’s 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 MX-5 Miata doesn’t offer drift compensation steering.
For a smoother ride and more stable handling, the C-Class Cabriolet’s wheelbase is 20.9 inches longer than on the MX-5 Miata (111.8 inches vs. 90.9 inches).
For better handling and stability, the average track (width between the wheels) on the C-Class Cabriolet is 2.7 inches wider in the front and 1.8 inches wider in the rear than the track on the MX-5 Miata.
The C 300 Cabriolet handles at .94 G’s, while the MX-5 Miata pulls only .88 G’s of cornering force in a Car and Driver skidpad test.
The front grille of the C-Class Cabriolet uses electronically controlled shutters to close off airflow and reduce drag when less engine cooling is needed. This helps improve highway fuel economy. The MX-5 Miata doesn’t offer active grille shutters.
The C-Class Cabriolet has standard seating for 4 passengers; the MX-5 Miata can only carry 2.
The C-Class Cabriolet has a much larger trunk with its top down than the MX-5 Miata (7 vs. 4.6 cubic feet). The C-Class Cabriolet has a much larger trunk with its top up than the MX-5 Miata (8.8 vs. 4.6 cubic feet).
With its convertible body style, locking rear seatbacks and remote trunk release lockout, the C-Class offers cargo security. The MX-5 Miata’s non-lockable remote release defeats cargo security.
The C-Class Cabriolet uses gas struts to support the hood for easier service access. The MX-5 Miata uses a prop rod to support its heavy hood. It takes two hands to open the hood and set the prop rod, the prop rod gets in the way during maintenance and service, and the prop rod could be knocked out, causing the heavy hood to fall on the person maintaining or servicing the car.
J.D. Power and Associates surveys of service recipients show that Mercedes service is better than Mazda. J.D. Power ranks Mercedes fifth in service department satisfaction. With a 59% lower rating, Mazda is ranked 25th.
The C-Class Cabriolet 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 MX-5 Miata doesn’t offer a remote starting system.
When three different drivers share the C-Class Cabriolet, the memory system makes it convenient for all three. Each setting activates different, customized memories for the driver’s seat (memory seat optional for the front passenger), steering wheel position and outside mirror angle. The MX-5 Miata doesn’t offer a memory system.
The C-Class Cabriolet’s standard easy entry system raises the steering wheel, making it easier for the driver to get in and out. The MX-5 Miata doesn’t offer an easy entry system.
The C-Class Cabriolet offers an optional heads-up display that projects speed and navigation instruction readouts in front of the driver’s line of sight, allowing drivers to view information without diverting their eyes from the road. The MX-5 Miata doesn’t offer a heads-up display.
The C-Class Cabriolet’s power parking brake sets with one touch and releases with one touch or automatically. The MX-5 Miata has a lever-type parking brake that has to be strenuously raised to engage properly. It has to be lifted up more and a button depressed to release it.
The power windows standard on both the C-Class Cabriolet and the MX-5 Miata have locks to prevent small children from operating them. When the lock on the C-Class Cabriolet is engaged the driver can still operate all of the windows, for instance to close one opened by a child. The MX-5 Miata prevents the driver from operating the other windows just as it does the other passengers.
The C-Class Cabriolet’s front and rear power windows all open or close fully with one touch of the switches, making it more convenient at drive-up windows and toll booths, or when talking with someone outside the car. The MX-5 Miata’s power window switches have to be held the entire time to close them fully. Only its front windows open automatically.
If the windows are left open on the C-Class Cabriolet the driver can close them all at the outside door handle or from a distance using the remote. On a hot day the driver can lower the windows from a distance using the keyless remote. The driver of the MX-5 Miata can only operate the windows from inside the vehicle, with the ignition on.
In case of a sudden change of weather, the C-Class Cabriolet has a standard remote convertible top that can be raised from a distance to protect the interior of the vehicle from damage. The MX-5 Miata doesn’t offer a remote top, so the driver will have to run to the car, get in, turn the ignition on (with available power top) and raise the top to prevent the interior from being damaged.
The C-Class Cabriolet’s power window, power lock, power mirror and cruise control switches are lit from behind, making them plainly visible and easier to operate at night. The MX-5 Miata’s power mirror switches are unlit, making them difficult to find at night and operate safely.
The C-Class Cabriolet’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 MX-5 Miata Sport/Club’s standard manually variable intermittent wipers have to be constantly adjusted.
The C-Class Cabriolet has a standard automatic headlight on/off feature. When the ignition is on, the headlights automatically turn on at dusk and off after dawn. The MX-5 Miata has an automatic headlight on/off feature standard only on the Grand Touring.
To shield the driver and front passenger’s vision over a larger portion of the windshield and side windows, the C-Class Cabriolet has standard extendable sun visors. The MX-5 Miata doesn’t offer extendable visors.
The C-Class Cabriolet’s sun-visors swivel front-to-side to block glare from the side windows. The MX-5 Miata’s visors are fixed into the windshield header.
The C-Class Cabriolet’s standard outside mirrors include heating elements to clear off the mirrors for better visibility. Mazda only offers heated mirrors on the MX-5 Miata Grand Touring.
When the C-Class Cabriolet 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 MX-5 Miata’s mirror doesn’t automatically adjust for backing.
Optional air-conditioned seats in the C-Class Cabriolet keep the driver and front passenger comfortable and take the sting out of hot seats in summer. The MX-5 Miata doesn’t offer air-conditioned seats.
On extremely cold winter days, the C-Class Cabriolet’s optional heated steering wheel provides comfort, allowing the driver to steer safely and comfortably before the car heater warms up. The MX-5 Miata doesn’t offer a heated steering wheel.
The C-Class Cabriolet’s 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. The MX-5 Miata doesn’t offer dual zone air conditioning.
A built-in pollen filter removes pollen, exhaust fumes and other pollutants from the C-Class Cabriolet’s passenger compartment. This helps prevent lung and/or sinus irritation, which can trigger allergies or asthma. The MX-5 Miata doesn’t offer a filtration system.
To keep a safe, consistent following distance, the C-Class Cabriolet offers an optional Active Distance Assist 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 MX-5 Miata doesn’t offer an adaptive cruise control.
The C-Class Cabriolet’s optional Active Parking Assist can parallel park or back into a parking spot by itself, stopping and changing direction automatically. The MX-5 Miata doesn’t offer an automated parking system.
The Mercedes C-Class comes in coupe, convertible and sedan bodystyles; the Mazda MX-5 Miata isn’t available as a coupe or sedan.
Consumer Reports® recommends both the Mercedes C-Class Cabriolet and the Mazda MX-5 Miata, based on reliability, safety and performance.
J.D. Power and Associates rated the C-Class Cabriolet first among compact premium cars in owner reported satisfaction. This includes how well the vehicle performs and satisfies its owner’s expectations. The MX-5 Miata isn’t in the top three in its category.
The Mercedes C-Class outsold the Mazda MX-5 Miata by over seven to one during the 2019 model year.
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