Compare the2023 BMW 8 SeriesVS 2021 Mercedes AMG S-Class Cabriolet

The 8 Series 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 AMG S-Class Cabriolet 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.

Both the 8 Series and the AMG S-Class Cabriolet 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, crash mitigating brakes, daytime running lights, lane departure warning systems, rearview cameras, driver alert monitors, available blind spot warning systems, rear parking sensors and rear cross-path warning.

The 8 Series’ corrosion warranty is 7 years longer than the AMG S-Class Cabriolet’s (12 vs. 5 years).

BMW pays for scheduled maintenance on the 8 Series 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 AMG S-Class Cabriolet.

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 Mercedes vehicles. J.D. Power ranks BMW above average in initial quality. With 24 more problems per 100 vehicles, Mercedes is rated below average.

J.D. Power and Associates’ 2022 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 above average in long-term dependability. With 5 more problems per 100 vehicles in the first three years of ownership, Mercedes is rated below average.

From surveys of all its subscribers, Consumer Reports’ January 2021 Auto Issue reports that BMW vehicles are more reliable than Mercedes vehicles. Consumer Reports ranks BMW 8 places higher in reliability than Mercedes.

As tested in Car and Driver the M850i 4.4 turbo V8 is faster than the Mercedes AMG S-Class Cabriolet:

On the EPA test cycle the 8 Series Convertible gets better mileage than the AMG S-Class Cabriolet:

Regenerative brakes improve the 8 Series’ fuel efficiency by converting inertia back into energy instead of wasting it. The AMG S-Class Cabriolet doesn’t offer a regenerative braking system.

The 8 Series’ optional 245/35R20 front and 275/30R20 rear tires provide better handling because they have a lower 35 series front and 30 series rear profile (height to width ratio) that provides a stiffer sidewall than the AMG S-Class Cabriolet’s 40 series front and 35 series rear tires.

Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires available on the 8 Series can be driven up to 50 miles without any air pressure, allowing you to drive to a service station for a repair. The AMG S-Class Cabriolet doesn’t offer run-flat tires.

The 8 Series M850i has active sway bars, which help keep it flat and controlled during cornering, but disconnect at lower speeds to smooth the ride and offer greater off-road suspension articulation. This helps keep the tires glued to the road on-road and off. The AMG S-Class Cabriolet doesn’t offer an active sway bar system.

The M850i offers an available active suspension system, which counteracts cornering forces actively, limiting body roll and improving handling and stability. Mercedes doesn’t offer an active suspension on the AMG S-Class Cabriolet.

For better maneuverability, the 8 Series’ turning circle is .8 feet tighter than the AMG S-Class Cabriolet’s (38.2 feet vs. 39 feet).

The BMW 8 Series may be more efficient, handle and accelerate better because it weighs about 150 to 900 pounds less than the Mercedes AMG S-Class Cabriolet.

The 8 Series is 7.7 inches shorter than the AMG S-Class Cabriolet, making the 8 Series easier to handle, maneuver and park in tight spaces.

The front grille of the 8 Series uses electronically controlled shutters to close off airflow and reduce drag when less engine cooling is needed. This helps improve highway fuel economy. The AMG S-Class Cabriolet doesn’t offer active grille shutters.

The 8 Series Convertible has a much larger trunk with its top down than the AMG S-Class Cabriolet with its top down (12.4 vs. 8.8 cubic feet).

The 8 Series’ standard rear seats fold to accommodate long and bulky cargo. The AMG S-Class Cabriolet doesn’t offer folding rear seats, only a ski pass-through.

J.D. Power and Associates surveys of service recipients show that BMW service is better than Mercedes. J.D. Power ranks BMW 7th in service department satisfaction (above the industry average). With a 17% lower rating, Mercedes is ranked 18th.

The 8 Series has a standard heated steering wheel to take the chill out of steering on extremely cold winter days before the car heater warms up. A heated steering wheel costs extra on the AMG S-Class Cabriolet.

The BMW 8 Series comes in coupe, convertible and sedan bodystyles; the Mercedes AMG S-Class isn’t available as a sedan.

The 8 Series is available in both rear-wheel drive and all-wheel drive configurations. The AMG S-Class Cabriolet doesn’t offer a two-wheel drive configuration.