20 MPG combined isn’t going to top any fuel efficiency charts, but it probably won’t scare away someone considering a 2018 Mercedes-Benz S560 Convertible either. This is a buyer who’s used to, and can afford, prioritizing open-air luxury and easy V8 power over saving gas. They want an experience and that involves the recognizable sound of a twin-turbocharged 4.0-liter V8 that produces 463 horsepower in a handcrafted, leather interior.

City and highway performance

The EPA estimates the S560 Convertible gets 17 MPG in the city and 26 MPG on the highway. The city number shows how much harder the engine works to get going from a stop in urban driving. On the other hand, the 26 MPG highway number is reached when there are fewer changes in speed, and the 9-speed automatic transmission can pick the best gear. Of course, if you frequently use the S560’s strong engine, expect lower MPG in both situations.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2018 Mercedes-Benz S560 Convertible at $2,900. This is based on driving 15,000 miles a year, with 45% in the city and 55% on the highway, using the national average gas price. Remember that this is just an estimate. Your actual fuel costs will depend on how you drive, the kind of gas you use, and changes in gas prices. Many S560 owners will probably drive more than 15,000 miles, enjoying the open top in nice weather.

Real-world expectations

EPA ratings are a helpful guide, but the S560 Convertible’s real-world fuel economy will change based on how you drive, the roads you drive on, and the weather. Expect numbers close to the EPA estimates if you drive gently, mostly on the highway, but the city MPG will drop with quick acceleration and frequent stops. Using the sportier driving modes will likely lower fuel efficiency, but it will offer a more exciting driving experience. Owners who want better MPG might try using the “Comfort” or “Eco” modes regularly.

How it compares

The S560 Convertible is in a special class where fuel efficiency isn’t the main thing, but comparisons still matter. The BMW M850i Convertible, a direct competitor, gets a slightly better EPA-estimated combined MPG of 20 MPG despite having similar performance. The Porsche 911 Cabriolet, specifically the Carrera S model, offers a much better 21 MPG combined and is a bit sportier. But you get less interior space and less luxury compared to the S560. If you’re exploring the market, you should check out all Mercedes Benz fuel economy data to see how the S560 compares within the brand’s broader lineup, and maybe even specifically S560 MPG across all years.

Tips to maximize efficiency

While getting the best MPG might not be the most important goal for an S560 Convertible owner, you can still take steps to improve it. Making sure your tires have the right amount of air is critical. Tires with low air pressure create more resistance, making the engine work harder and use more gas. Check your tire pressure often and fill them to the levels suggested by the manufacturer, which you can find on the door frame.

Avoid fast acceleration and hard stops. The S560 Convertible’s twin-turbo V8 can accelerate quickly, but doing that often uses more gas. Accelerate in a smooth, easy manner, and watch the road ahead to reduce hard braking, which wastes energy.

Don’t let the engine run when you aren’t moving. Letting the engine run while stopped uses gas without going anywhere. If you think you’ll be stopped for more than a minute, turn off the engine. The S560 has a start-stop system that automatically shuts off the engine at stoplights, but if you turn this feature off, be aware of running the engine when it’s not needed.

Use cruise control on the highway. Keeping a steady speed on the highway can improve MPG. Use cruise control to keep your speed steady and avoid accelerating and slowing down for no reason. This works especially well on long, flat roads where you can easily keep the gas pedal still.

Choose premium fuel. The S560’s strong engine needs premium fuel (91 octane or higher) to work its best. Using lower-octane fuel can reduce performance and possibly damage the engine over the long term. Keeping the engine in good working order helps it last longer and get better MPG.