22 MPG combined won’t win any fuel efficiency awards, but for the 2021 Mercedes-Benz AMG C43 4matic Convertible, it’s a price many are willing to pay for the thrills this machine delivers. This isn’t just a car; it’s an experience. Buyers aren’t prioritizing maximum fuel efficiency; they’re seeking a potent engine, sharp handling, and open-air driving pleasure with a touch of luxury. This MPG figure reflects the performance-oriented nature of the C43, showing that driving enjoyment takes precedence over outright frugality for this particular niche of the automotive market.

City and highway performance

The EPA estimates the AMG C43 Convertible at 19 MPG in the city and 27 MPG on the highway. The city figure reflects the stop-and-go driving inherent in urban environments, where the engine spends more time idling or accelerating from a standstill, both situations that strain fuel economy. The highway number, however, is reasonably respectable, showcasing the benefit of the nine-speed automatic transmission allowing the engine to cruise at lower RPMs when maintaining consistent speeds. Keep in mind that aggressive driving habits, even on the highway, will significantly reduce that 27 MPG figure. The 3.0L V6 isn’t shy about unleashing all 385 horses to their fullest extent, with a resultant penalty at the pump.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 Mercedes-Benz AMG C43 4matic Convertible at precisely $2,650. This calculation is based on driving 15,000 miles per year, using a national average fuel price that’s updated regularly by the EPA. This number is a useful benchmark for prospective buyers, allowing them to factor in the cost of ownership alongside the vehicle’s purchase price, insurance, and maintenance. It’s not small change, potentially outweighing the cost difference for some to consider a less performance-oriented vehicle, but for buyers specifically seeking an AMG convertible, it’s seen as the cost of admission.

Real-world expectations

While the EPA provides a standardized estimate, real-world fuel economy invariably varies based on individual driving habits and conditions. Expect aggressive driving, especially frequent hard acceleration and spirited cornering, to drag the combined MPG down into the high teens. Conversely, a careful driver who anticipates traffic, avoids excessive idling, and uses cruise control on the highway can likely match or slightly exceed the EPA’s estimates. The key is resisting the temptation to fully exploit the engine’s power at every opportunity, because all those glorious sounds and performance will cost you when it’s time to fill up the tank.

How it compares

The AMG C43 Convertible exists in a niche market, blending performance and open-top driving. Competitors like the BMW M440i Convertible xDrive achieve around 25 MPG combined, offering a slightly more efficient alternative, albeit with a different driving character. The Audi S5 Cabriolet, rated at 24 MPG combined, presents another option with similar performance credentials but may appeal to buyers who prefer Audi’s interior design and technology. Even the less powerful Porsche 718 Boxster comes in around 22 MPG, while offering a completely different mid-engine driving experience. The C43 buyer knowingly sacrifices a few MPGs for the specific Mercedes-AMG package that is uniquely its own.

Tips to maximize efficiency

Use the car’s driving modes. Selecting “Comfort” mode will soften the throttle response and encourage earlier upshifts, promoting more fuel-efficient driving, especially around town. Resist the urge to keep it permanently in “Sport+” unless you’re actively enjoying a spirited drive, as that mode prioritizes performance over economy.

Maintain proper tire inflation. Underinflated tires increase rolling resistance, forcing the engine to work harder and consuming more fuel. Check your tire pressures regularly and inflate them to the recommended levels listed on the doorjamb sticker for the best balance of handling and efficiency.

Avoid unnecessary weight in the trunk. Extra cargo adds to the vehicle’s overall mass, impacting fuel economy. Only carry essential items and remove any unnecessary clutter to minimize the burden on the engine. Similarly, if the rear seats are unused, make sure that they are empty and, if possible, in their upright position to improve airflow.

Plan your routes strategically. Avoiding congested areas and peak traffic times minimizes stop-and-go driving, which is the most fuel-intensive scenario. Opt for routes that allow for more consistent speeds and fewer interruptions whenever possible.

Consider the type of fuel you’re using. While premium fuel is recommended for the C43, ensure that you’re using the correct octane rating as specified in the owner’s manual. Using a lower octane fuel than recommended can negatively affect performance and potentially damage the engine, ultimately reducing fuel efficiency in the long run. See all Mercedes Benz fuel economy data.