18 MPG combined is the cold, hard number staring back at anyone considering a 2015 Mercedes-Benz CLS63 AMG S 4matic. This isn’t a fuel sipper. It’s not designed to be. This is a borderline supercar disguised as a sleek four-door coupe. Those who prioritize hyper-efficient commuting simply aren’t in the target demographic. The CLS63 AMG buyer seeks a blend of raw power, a luxurious ride, and eye-catching design, and they’re willing to pay the price at the pump to get it.

City and highway performance

The EPA estimates the CLS63 AMG S at 16 MPG in the city and 22 MPG on the highway. The city figure reflects the constant stop-and-go driving that plagues urban environments, situations where the 5.5L twin-turbo V8 constantly needs to overcome its own significant weight and the limitations of even the most advanced stop/start systems. The highway number illustrates the engine’s relative efficiency at a steady cruise, but even here, the temptation to exercise the prodigious power on tap likely degrades the overall average. Driven sedately, 22 MPG is achievable, but restraint is not typically a CLS63 AMG driver’s strong suit.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2015 Mercedes-Benz CLS63 AMG S 4matic at $3,200. This figure is based on driving 15,000 miles per year and using the national average fuel price at the time of calculation. Of course, individual fuel costs will vary depending on driving habits and local fuel prices. However, consider this figure a benchmark and prepare for it to potentially be higher if you frequently tap into the AMG’s performance reserves.

Real-world expectations

Expect the EPA estimate to be a *best-case* scenario. Aggressive acceleration, frequent trips into boost, and the irresistible exhaust note all contribute to lower real-world MPG. If most of your driving is in congested city conditions, hitting 16 MPG consistently might be a struggle. Conversely, if you primarily use the car for long highway cruises, achieving close to 22 MPG is more realistic. Ultimately, your driving style will be the biggest determinant of your actual fuel economy.

How it compares

The CLS63 AMG’s fuel economy lags behind some of its competitors, but the differences are often marginal. For instance, consider the 2015 BMW M6 Gran Coupe. Its EPA estimates were only slightly better, at 17 MPG city and 24 MPG highway. The Audi RS7, with its 4.0-liter twin-turbo V8, achieved similar figures. The Porsche Panamera Turbo, while offering comparable performance, lands around 18 MPG combined. The choice comes down to brand preference, styling, and performance characteristics, not solely on a single MPG point or two. Those wanting to do deeper dives should look at CLS63 MPG across all years, as well as options from other manufacturers.

Tips to maximize efficiency

Smooth, gradual acceleration is key. Avoid flooring the accelerator unless absolutely necessary. The CLS63 AMG’s engine is incredibly responsive, and even moderate throttle inputs deliver plenty of power. Light acceleration will significantly reduce fuel consumption.

Use the car’s driving modes effectively. Select the “Comfort” or “Eco” mode when possible, especially in low-speed traffic or on the highway. These modes adjust throttle response and shift points to prioritize fuel efficiency. Conversely, “Sport” or “Sport+” modes will maximize performance but will severely impact fuel economy.

Maintain proper tire inflation. Underinflated tires increase rolling resistance, which directly reduces fuel economy. Check tire pressure regularly and inflate to the recommended level (found on the driver’s side door jamb or in the owner’s manual). Consider using a high-quality tire pressure gauge for accurate readings.

Consider the weight you’re carrying. Empty the trunk of unnecessary items, as extra weight increases fuel consumption. Every additional pound requires more energy to accelerate and maintain speed. Regular decluttering can contribute to improved MPG.

Keep up with regular maintenance. A well-maintained engine operates more efficiently. Ensure that oil changes, spark plug replacements, and other scheduled services are performed on time. A properly tuned engine will optimize fuel economy and prolong its lifespan. For further information, be sure to check all Mercedes Benz fuel economy data for more information.