18 MPG combined is what you get when driving the 2018 Mercedes-Benz AMG CLS63 S 4matic. This isn’t a car purchased by people who want to save gas; it’s a four-door coupe that delivers strong performance with luxury. The CLS63 S buyer wants fast acceleration and exclusivity over saving fuel, accepting the realities of a potent, hand-built V8 engine in exchange for its power.

City and highway performance

The CLS63 S doesn’t pretend to be anything it isn’t. Its EPA ratings show a contrast between city and highway driving. The 16 MPG city figure reveals the fuel-using reality of stop-and-go traffic and the urge to tap into the engine’s power. On the open road, the 22 MPG highway rating offers a slight reprieve, achievable with a light foot and careful use of cruise control. But even on the highway, the exhaust note and passing power can quickly reduce attempts at maximizing fuel efficiency. This car begs to be driven, and its performance capabilities make restraint hard.

Annual fuel cost

According to the EPA, the estimated annual fuel cost for the 2018 Mercedes-Benz AMG CLS63 S 4matic is $3,200. This figure is based on driving 15,000 miles per year, with 55% of those miles driven in the city and 45% on the highway. The calculation also uses the national average fuel price, which fluctuates but provides a standard baseline for comparison. While this number might seem high compared to more fuel-efficient vehicles, it’s simply the cost for those who want this level of performance and luxury. The CLS63 S buyer understands that power comes at a price, and fuel consumption is part of that.

Real-world expectations

The EPA figures provide a useful benchmark, but real-world fuel economy often changes based on driving habits. Fast acceleration, frequent hard braking, and extended idling will lower the MPG. On the other hand, careful throttle management and consistent highway speeds can bring you closer to the EPA estimates. However, it’s unlikely that most CLS63 S owners will consistently achieve the rated 22 MPG on the highway. The appeal of the engine’s power is too strong, and the temptation to unleash its potential is always there. Expect to see numbers closer to the city rating in mixed driving, especially if you enjoy exploring the car’s capabilities.

How it compares

When considering similar high-performance luxury models, the fuel economy of the CLS63 S is typical for its class. The BMW M6 Gran Coupe, for instance, is rated at 17 MPG combined, highlighting the fuel needs of high-output engines. Even newer models like the Mercedes-AMG GT 63 S 4-Door Coupe are only a little better, achieving around 19 MPG combined. Comparing the AMG MPG across all years, the CLS63 S reflects the inefficiency of the time before hybrid and electric adoption. The Porsche Panamera Turbo, another competitor, achieves similar numbers in its non-hybrid configurations. Buyers in this segment are generally less concerned with fuel efficiency and more focused on performance and prestige, making the slight variations in MPG less of a deciding factor. They are more interested in how the car drives and feels than by saving a few dollars at the pump, while also seeking out all Mercedes Benz fuel economy data.

Tips to maximize efficiency

While the CLS63 S isn’t designed for saving fuel, there are ways to improve its fuel consumption. Avoid excessive idling, as the engine burns fuel even when stationary. Plan your routes to minimize stop-and-go traffic, and try to maintain consistent speeds on the highway.

Gentle acceleration is important. The CLS63 S has power available, but using it sometimes will improve fuel efficiency. Feather the throttle and avoid sudden bursts of speed when possible. It’s a change in driving style that might feel at odds with the car’s character, but it has a measurable impact.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressure regularly and maintain it at the recommended level specified on the door jamb sticker.

Consider using the car’s “Comfort” driving mode when performance isn’t a priority. This mode adjusts the engine and transmission settings to prioritize fuel efficiency over immediate power delivery. It tempers the throttle response and encourages earlier upshifts.