25 MPG combined. That’s the headline figure for the 2017 Mercedes-Benz C300 4matic Convertible, equipped with its 2.0L turbocharged four-cylinder engine. No one buys this car primarily for fuel efficiency. It’s a stylish, open-air statement, an expression of personal enjoyment. The fuel economy, while not stellar, is an acceptable trade-off for the experience of top-down motoring with a touch of luxury. C300 buyers prioritize the three-pointed star, the elegant design, and the feeling of the sun on their faces far more than squeezing every last mile from a gallon of premium unleaded.

City and highway performance

The EPA numbers break down to 22 MPG in the city and 29 MPG on the highway. The city figure reflects the realities of stop-and-go driving, where the engine works harder and the fuel consumption is higher. The 9-speed automatic transmission, while generally smooth and responsive, can sometimes feel a touch hesitant in urban situations, contributing to slightly lower efficiency. On the open road, however, the C300 Convertible settles into a comfortable cruise, and the 2.0L engine, with its ample torque, can effortlessly maintain highway speeds while returning respectable fuel economy. The 29 MPG highway rating suggests that longer journeys will be reasonably efficient, provided you resist the urge to fully exploit the engine’s power.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2017 Mercedes-Benz C300 4matic Convertible at $2,300. This figure is based on driving 15,000 miles per year and using the national average fuel price at the time of calculation. This number gives prospective buyers a tangible estimate of what they can expect to spend on fuel annually. Of course, your actual fuel costs may vary drastically based on several factors, including changes in fuel prices, how aggressively you drive, and the proportion of city versus highway miles you accumulate.

Real-world expectations

While the EPA provides a standardized benchmark, real-world MPG often deviates. Aggressive driving, frequent use of the air conditioning, and consistent short trips, will certainly lower your actual fuel economy, potentially dipping below 20 MPG in mixed driving. Conversely, a gentle driving style, combined with predominantly highway cruising, could see you approach or even slightly exceed the 29 MPG highway rating. The key to maximizing fuel efficiency in the C300 Convertible is to avoid excessive acceleration and maintain a steady speed whenever possible.

How it compares

The Audi A5 Cabriolet, another popular luxury convertible, offers comparable performance and fuel economy. Depending on specific model year and engine configuration, the A5 generally hovers around 24 MPG combined. BMW’s 430i Convertible, similarly equipped with a 2.0L turbo engine, delivers about 25 MPG combined. These figures underscore that fuel economy is not a unique selling point in this segment. Opting for the more powerful C43 AMG variant of the C-Class convertible, while vastly more thrilling, will result in a significant MPG drop, likely falling to around 20 MPG combined. Comparing the C300 MPG across all years highlights the consistency of this model’s fuel economy performance over time.

Tips to maximize efficiency

Take advantage of the C300’s “Eco” driving mode. This setting adjusts the throttle response and transmission shift points to prioritize fuel economy, which can make a noticeable difference, especially in city driving. It might not be the sportiest experience, but it will save you money at the pump.

Maintain proper tire inflation. Under-inflated tires increase rolling resistance, forcing the engine to work harder and reducing fuel efficiency. Check your tire pressures regularly and inflate them to the recommended level, which can be found on a sticker inside the driver’s side door or in the owner’s manual. This is a simple, yet often overlooked, way to improve your MPG.

Avoid excessive idling. Letting the engine idle for extended periods consumes fuel without covering any distance. If you’re stopped for more than a minute or two, it’s more efficient to turn off the engine. Modern engines are designed to restart quickly and reliably, minimizing any potential wear and tear from frequent starts.

Be mindful of your route. Planning your trips to avoid congested areas and minimize stop-and-go traffic can significantly improve your fuel economy. Using navigation apps to identify the most efficient route can help you save fuel and time.

Since the vehicle is equipped with 4matic all-wheel drive, keeping up with recommended maintenance for the drivetrain is critical. Servicing the differentials and transfer case will keep them running efficiently and prevent any extra drag, preventing a drop in fuel economy. You can view all Mercedes Benz fuel economy data on this site.