Compare the2023 BMW 4 Series ConvertibleVS 2023 Mazda MX-5 Miata

Safety
Warranty
Reliability
Engine
Fuel Economy and Range
Environmental Friendliness
Transmission and Drivetrain
Brakes and Stopping
Tires and Wheels
Suspension and Handling
Passenger Space
Cargo Capacity
Servicing Ease
Ergonomics
Model Availability
Recommendations

Safety

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The 4 Series Convertible’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 BMW 4 Series Convertible has standard driver and front passenger side knee airbags mounted low on the dashboard. These airbags helps prevent the driver and front passenger from sliding under their seatbelts or the main frontal airbags; this keeps them better positioned during a collision for maximum protection. Knee airbags also help keep the legs from striking the dashboard, preventing knee and leg injuries in the case of a serious frontal collision. The MX-5 Miata doesn’t offer knee airbags.

The 4 Series Convertible’s standard pretensioning seatbelts also sense rear collisions and remove slack from the seatbelts to help protect the occupants from whiplash and other injuries. The MX-5 Miata doesn’t offer a whiplash protection system.

The 4 Series Convertible has a standard PostCrash iBrake, which automatically applies the brakes in the event of a crash to help prevent secondary collisions and prevent further injuries. The MX-5 Miata doesn’t offer a post collision braking system: in the event of a collision that triggers the airbags, more collisions are possible without the protection of airbags that may have already deployed.

Over 200 people are killed each year when backed over by motor vehicles. The 4 Series Convertible M440i offers an optional Active Park Distance Control that uses rear sensors to monitor for objects to the rear and automatically applies the brakes to prevent a collision. The MX-5 Miata doesn’t offer backup collision prevention brakes.

The 4 Series Convertible 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 4 Series Convertible M440i offers an optional Surround View to allow the driver to see objects all around the vehicle on a screen. The MX-5 Miata only offers a rear monitor.

The 4 Series Convertible’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.

Compared to metal, the 4 Series Convertible’s plastic fuel tank can withstand harder, more intrusive impacts without leaking; this decreases the possibility of fire. The Mazda MX-5 Miata has a metal gas tank.

Both the 4 Series Convertible 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, crash mitigating brakes, daytime running lights, lane departure warning systems, blind spot warning systems, rearview cameras and rear cross-path warning.

The BMW 4 Series Convertible weighs 1422 to 1951 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.

Warranty

The 4 Series Convertible 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 or 14,000 miles sooner.

The 4 Series Convertible’s corrosion warranty is 7 years longer than the MX-5 Miata’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. Mazda doesn’t pay scheduled maintenance for the MX-5 Miata.

Reliability

The battery on the 4 Series Convertible is in the trunk, which protects it from hot underhood temperatures that can degrade battery life. By keeping the 4 Series Convertible’s battery 20 to 30 degrees cooler, its life is increased by years. The MX-5 Miata’s battery is in the hot engine compartment.

J.D. Power and Associates rated the 4 Series Convertible third among compact premium cars in their 2022 Initial Quality Study. The MX-5 Miata isn’t in the top three in its category.

J.D. Power and Associates’ 2022 Initial Quality Study of new car owners surveyed provide the statistics that show that BMW vehicles are better in initial quality than Mazda vehicles. J.D. Power ranks BMW above average in initial quality. With 15 more problems per 100 vehicles, Mazda is rated lower.

From surveys of all its subscribers, Consumer Reports’ January 2023 Auto Issue reports that BMW vehicles are more reliable than Mazda vehicles. Consumer Reports ranks BMW third in overall reliability. Mazda is ranked fourth.

Engine

The 430i Convertible’s standard 2.0 turbo 4-cylinder produces 74 more horsepower (255 vs. 181) and 143 lbs.-ft. more torque (294 vs. 151) than the MX-5 Miata’s 2.0 DOHC 4-cylinder. The M440i Convertible’s standard 3.0 turbo 6-cylinder hybrid produces 201 more horsepower (382 vs. 181) and 217 lbs.-ft. more torque (368 vs. 151) than the MX-5 Miata’s 2.0 DOHC 4-cylinder.

Fuel Economy and Range

Regenerative brakes improve the 4 Series Convertible’s fuel efficiency by converting inertia back into energy instead of wasting it. The MX-5 Miata doesn’t offer a regenerative braking system.

In heavy traffic or at stoplights the 4 Series Convertible’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. If the conditions warrant or the driver wishes, the system can be manually disabled at any time for the duration of a trip. The MX-5 Miata doesn’t offer an automatic engine start/stop system.

The 4 Series Convertible has 3.7 gallons more fuel capacity than the MX-5 Miata (15.6 vs. 11.9 gallons), for longer range between fill-ups.

Environmental Friendliness

In its Green Vehicle Guide, the U.S. Environmental Protection Agency (EPA) rates the BMW 4 Series Convertible higher (5 to 7 out of 10) than the Mazda MX-5 Miata (3). This means the 4 Series Convertible produces up to 24.5 pounds less smog-producing pollutants than the MX-5 Miata every 15,000 miles.

Transmission and Drivetrain

The BMW 4 Series Convertible comes standard with an automatic transmission, for driver comfort, especially in the city. Automatic costs extra on the MX-5 Miata.

An eight-speed automatic is standard on the BMW 4 Series Convertible, 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 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 Mazda MX-5 Miata is not available with all wheel drive.

The 4 Series Convertible’s launch control uses engine electronics to hold engine RPM’s precisely in order to provide the most stable and rapid acceleration possible, using all of the available traction. The MX-5 Miata doesn’t offer launch control.

Brakes and Stopping

For better stopping power the 4 Series Convertible’s brake rotors are larger than those on the MX-5 Miata:

	4 Series Convertible	4 Series Convertible M440i	MX-5 Miata
Front Rotors	13 inches	13.7 inches	11 inches
Rear Rotors	13 inches	13.6 inches	11 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 on the MX-5 Miata are solid, not vented.

Tires and Wheels

For better traction, the 4 Series Convertible has larger standard tires than the MX-5 Miata (225/45R18 vs. 195/50R16). The 4 Series Convertible’s optional tires are larger than the largest tires available on the MX-5 Miata (F:225/40R19 & R:255/35R19 vs. 205/45R17).

The 430i’s standard tires provide better handling because they have a lower 45 series profile (height to width ratio) that provides a stiffer sidewall than the MX-5 Miata Sport’s standard 50 series tires. The 4 Series Convertible’s optional 225/40R19 front and 255/35R19 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 4 Series Convertible has standard 18-inch wheels. Smaller 16-inch wheels are standard on the MX-5 Miata Sport. The 4 Series Convertible’s optional 19-inch wheels are larger than the 17-inch wheels on the MX-5 Miata Club/Grand Touring.

The BMW 4 Series Convertible’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 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 MX-5 Miata doesn’t offer run-flat tires.

Suspension and Handling

The 4 Series Convertible offers an available driver-adjustable suspension system. It allows the driver to choose between an extra-supple ride, reducing fatigue on long trips, or a sport setting, which allows maximum control for tricky roads. The MX-5 Miata’s suspension doesn’t offer adjustable shock absorbers.

The 4 Series Convertible 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.

For a smoother ride and more stable handling, the 4 Series Convertible’s wheelbase is 21.3 inches longer than on the MX-5 Miata (112.2 inches vs. 90.9 inches).

For better handling and stability, the track (width between the wheels) on the 4 Series Convertible is 3.4 inches wider in the front and 3.5 inches wider in the rear than on the MX-5 Miata.

Passenger Space

The 4 Series Convertible has standard seating for 4 passengers; the MX-5 Miata can only carry 2.

Cargo Capacity

The 4 Series Convertible has a much larger trunk with its top down than the MX-5 Miata (10.6 vs. 4.6 cubic feet).

A low lift-over trunk design makes loading and unloading the 4 Series Convertible easier. The 4 Series Convertible’s trunk lift-over height is 26.5 inches, while the MX-5 Miata’s liftover is 32 inches.

With its convertible body style, valet key, locking rear seatbacks and remote trunk release lockout, the 4 Series offers cargo security. The MX-5 Miata’s non-lockable remote release defeats cargo security.

To make loading and unloading groceries and cargo easier, especially for short adults, the 4 Series Convertible offers an optional power trunk, which opens and closes automatically by pressing a button, or optionally by just waving your foot, completely leaving your hands free. The MX-5 Miata doesn’t offer a power trunk.

Servicing Ease

The 4 Series Convertible 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 BMW service is better than Mazda. J.D. Power ranks BMW 7th in service department satisfaction (above the industry average). With a 10% lower rating, Mazda is ranked 11th.

Ergonomics

The 4 Series Convertible offers a 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 two different drivers share the 4 Series Convertible, the memory system makes it convenient for both. Each setting activates different, customized memories for the driver’s seat position, outside mirror angle, climate settings and radio stations. The MX-5 Miata doesn’t offer a memory system.

The 4 Series Convertible offers an optional heads-up display that projects speed, tachometer, warning 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 4 Series Convertible’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 4 Series Convertible’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 4 Series Convertible the driver can close them all at the outside door handle. 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 4 Series Convertible offers an optional remote convertible top that can be raised from a distance to protect the interior of the vehicle from damage. On a hot day the 4 Series Convertible offers an optional remote opening feature, to lower the top from outside. 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 4 Series Convertible’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 4 Series Convertible’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 4 Series Convertible 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.

The 4 Series Convertible’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 4 Series Convertible’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 4 Series Convertible 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 4 Series Convertible 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 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 MX-5 Miata doesn’t offer a heated steering wheel.

The 4 Series Convertible’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 4 Series Convertible’s passenger compartment. This helps prevent lung and/or sinus irritation which can trigger allergies or asthma. The MX-5 Miata’s air conditioner doesn’t offer a filtration system.

To keep a safe, consistent following distance, the 4 Series Convertible offers an optional Active Cruise Control, 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 4 Series Convertible M440i’s optional Parking Assistant Plus can parallel park or back into a parking spot by itself, starting, stopping and changing direction automatically. The MX-5 Miata doesn’t offer an automated parking system.

Model Availability

The BMW 4 Series comes in coupe, convertible and four door hatchback bodystyles; the Mazda MX-5 Miata isn’t available as a coupe or four door.

Recommendations

The BMW 4 Series outsold the Mazda MX-5 Miata by almost six to one during 2022.