24 MPG combined isn’t breaking any fuel economy records, but it’s a figure the 2020 Mercedes-Benz C300 Convertible’s typical buyer readily accepts. This isn’t a commuter car aimed at hypermilers; it’s a stylish, open-air experience bought by drivers prioritizing luxury, performance, and panache. They want the wind in their hair and the three-pointed star on the hood, and they understand there’s a trade-off. Getting the best fuel mileage is likely far down their list of priorities.

City and highway performance

The C300 Convertible’s 2.0L turbocharged four-cylinder engine, paired with a smooth 9-speed automatic transmission, yields EPA ratings of 21 MPG in the city and 29 MPG on the highway. The city figure reflects the stop-and-go driving this car will inevitably encounter, driving between restaurants, appointments, and weekend getaways. The highway number is more respectable, allowing for comfortable road trips with fewer fuel stops. However, keep in mind that enjoying the turbocharged engine’s performance, particularly with the top down, will certainly impact your real-world fuel consumption.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2020 Mercedes-Benz C300 Convertible at $2,400. This figure is based on driving 15,000 miles per year, with 45% of those miles driven in the city and 55% on the highway. It also assumes national average fuel prices. Actual fuel costs will vary depending on individual driving habits, local fuel prices, and the type of fuel used. The C300 Convertible requires premium gasoline, which is typically more expensive than regular unleaded, so that should be factored in.

Real-world expectations

While the EPA estimates provide a good baseline, real-world fuel economy often differs. Drivers in congested urban areas, or those with a lead foot, will likely see figures closer to the city estimate, even lower perhaps. Those who primarily drive on the highway, using cruise control and anticipating traffic, might achieve mileage closer to or even slightly above the 29 MPG highway rating. The degree to which you enjoy the C300’s sporting abilities will directly influence how frequently you’ll be visiting the gas station. Aggressive acceleration and frequent use of the Sport or Sport+ driving modes will deplete the fuel tank faster.

How it compares

Compared to its competitors, the C300 Convertible’s fuel economy is reasonable. The BMW 430i Convertible, with its 2.0L turbo-four, offers similar performance and achieves an EPA-estimated 27 MPG combined. The Audi A5 Cabriolet, also powered by a 2.0L turbo, manages around 27 MPG combined. These small differences rarely sway a buyer in this segment. Someone considering a C300 is likely drawn to its styling, interior appointments, and brand cachet, rather than obsessing over a 1-2 MPG difference. Those wanting all Mercedes Benz fuel economy data have resources to explore further. If they are brand agnostic, a less expensive Mazda MX-5 Miata offers a similar open-top driving experience with significantly better fuel economy, achieving around 30 MPG combined.

Tips to maximize efficiency

While fuel economy might not be the main worry, there are still ways to improve mileage in your C300 Convertible. Ensuring your tires are properly inflated reduces rolling resistance and improves mileage. Check the tire pressure regularly, referencing the sticker on the driver’s side door jamb for the recommended pressure.

Avoid aggressive acceleration and hard braking. Smooth, progressive driving conserves fuel by reducing the amount of energy wasted during each trip. Use the car’s Eco driving mode, which will alter engine mapping and transmission settings to prioritize fuel efficiency.

Minimize idling time. If you’re waiting for someone or anticipate being stopped for more than a minute, turn off the engine. Modern engines are designed to restart quickly and efficiently, and avoiding prolonged idling can save a surprising amount of fuel over time.

Plan your routes strategically. Avoid rush hour traffic and congested areas where possible. Using navigation apps to identify the most efficient routes can help you minimize stop-and-go driving and improve fuel consumption. Consider trying to improve your C300 MPG across all years.

Keep up with routine maintenance. Regular oil changes, air filter replacements, and other maintenance tasks ensure that your engine is running efficiently. A poorly maintained engine will consume more fuel than one that’s properly serviced.