24 MPG combined might not sound impressive, but the 2020 Mercedes-Benz C300 4matic Convertible isn’t built for maximum fuel efficiency. It’s a luxury convertible, designed for enjoying the open air and stylish cruising. People who prioritize top-down driving over exceptional gas mileage will likely find this acceptable. The C300 convertible delivers a comfortable and refined driving experience, and for many buyers, that is more important than class-leading fuel economy. They value the Mercedes-Benz badge, the exquisite interior, and the performance of its turbocharged engine, all contributing to the ownership experience.

City and highway performance

The EPA estimates the 2020 C300 4matic Convertible achieves 21 MPG in the city and 29 MPG on the highway. You can realistically achieve that highway number if you drive gently on long trips. However, quick acceleration and constant top-down driving at higher speeds will likely reduce that figure. The city MPG of 21 reflects typical stop-and-go traffic where the engine idles often. The 9-speed automatic transmission shifts with smoothness, prioritizing that over aggressively seeking maximum fuel efficiency.

Annual fuel cost

Based on the EPA’s estimates, the annual fuel cost for the 2020 Mercedes-Benz C300 4matic Convertible is approximately $2,400. This is based on 15,000 miles of driving per year, using the EPA’s combined MPG rating and national average fuel prices. Note that this is just an estimate, and your actual fuel costs will vary depending on your driving, local fuel prices, and the type of fuel you use. Premium fuel is recommended for optimal performance, and it typically costs more per gallon, further impacting the yearly expense. This cost is something buyers consider, but those attracted to the C300’s luxury and open-air experience are likely less concerned about fuel prices than someone purchasing a more economy-focused vehicle.

Real-world expectations

The EPA figures offer a guideline, but expect real-world MPG to change based on driving style and conditions. If you frequently enjoy the C300’s sporty performance, using the Sport or Sport+ driving modes can increase fuel consumption compared to the Comfort or Eco settings. Regular maintenance, like tire inflation and oil changes, also helps maintain good fuel efficiency. Quick acceleration, hard braking, and prolonged idling will all negatively impact your MPG. However, smooth, steady driving and anticipating traffic patterns can help you get closer to the EPA estimates.

How it compares

The 2020 C300 4matic Convertible’s fuel economy is competitive within the luxury convertible segment, but not the best. A BMW 430i Convertible achieves a slightly better 28 MPG combined. An Audi A5 Cabriolet has similar numbers in the low-mid 20s combined. These small differences are often minor to buyers, especially considering other factors weigh into their decisions. Buyers looking at all Mercedes Benz fuel economy data will find that the C300 is in the middle of the pack in overall efficiency.

Tips to maximize efficiency

Use the “Eco” driving mode whenever you can. This mode optimizes engine performance and transmission shift points for maximum fuel efficiency. It might slightly reduce responsiveness, but it can make a noticeable difference on the highway or in city traffic.

Make sure your tires are properly inflated. Underinflated tires create more rolling resistance, which increases fuel consumption. Check your tire pressure regularly and inflate them to the recommended pressure listed on the driver’s side doorjamb. This is a simple way to improve fuel economy.

Avoid unnecessary idling. Letting your engine idle for extended periods wastes fuel and can cause maintenance issues. If you’re waiting for more than a minute or two, turn off the engine. Modern starters are designed to handle frequent starts and stops.

Drive smoothly and anticipate traffic. Avoid quick acceleration and hard braking, as these actions consume more fuel. By anticipating traffic flow and maintaining a consistent speed, you can minimize fuel waste. This also makes for a more relaxed driving experience.

Keep up with scheduled maintenance. Regular oil changes, air filter replacements, and other maintenance services can help keep your engine running efficiently. Addressing minor issues promptly can prevent them from escalating into larger problems that negatively impact fuel economy. The 2.0L turbo demands the best from owners with its regular service intervals to keep that fuel economy where it should be, but also to enjoy the performance that makes the C300 MPG across all years worthwhile.