A combined 16 MPG is not a number that typically appears on the spec sheet of a vehicle designed for anything beyond blistering performance, and for the 2025 Mercedes-Benz AMG SL55 4MATIC+ 4.0L V8, that is precisely its mission. This is not a car engineered for Prius-level parsimony; it is a luxuriously appointed, highly advanced roadster built to thrill, to demolish autobahn stretches, and to make every journey feel like an event. Its fuel economy figures are a direct consequence of its potent, hand-built 4.0-liter twin-turbo V8 engine, its permanent all-wheel-drive system, and its inherent character as a grand touring sports car. The SL55 is not just a car, it is a statement, and that statement often involves a spirited drive, not a measured one. Buyers of this machine understand, and indeed expect, that exhilarating performance comes with a commensurate thirst.

City and highway performance

Delving deeper into the EPA ratings, the 2025 AMG SL55 reveals a City MPG of 13 and a Highway MPG of 21. These numbers paint a clear picture. In urban environments, where the twin-turbo V8 is constantly modulating power, accelerating from lights, and dealing with stop-and-go traffic, the efficiency naturally dips. The sheer mass of the vehicle, the drag of its wide tires, and the responsiveness of the automatic 9-speed transmission all contribute to this figure. Yet, 13 MPG in city driving for a 4.0-liter V8 performance roadster is not off-brand for its segment. On the highway, however, the picture improves significantly. Settling into a cruise, the nine-speed transmission allows the engine to lope along at lower RPMs, using its substantial torque to maintain speed with minimal effort. Here, the aerodynamics, while not optimized for absolute efficiency, combined with the V8 engine and 9-speed transmission, allow it to stretch each gallon further. Achieving 21 MPG on the open road with this level of performance potential, even if it will not win any eco-awards. For the driver who enjoys a properly executed road trip, those highway numbers offer a welcome respite from the city’s demands, confirming that the SL55 is not just for short, blistering sprints, but also for covering serious distances in supreme comfort and pace.

Annual fuel cost

The EPA estimates an annual fuel cost of $3,600 for the 2025 Mercedes-Benz AMG SL55 4MATIC+. This figure, precisely calculated by the EPA, assumes 15,000 miles driven per year with a mix of city and highway driving, using national average fuel prices for premium gasoline. For the individual considering the SL55, this $3,600 is a line item, not a deal-breaker. The cost of fuel pales in comparison to the vehicle’s initial purchase price, its insurance premiums, and its routine high-performance maintenance. Those who commit to the AMG SL55 do so for an unparalleled driving experience, for its exquisite craftsmanship, and for its unique blend of luxury and performance. The fuel bill is simply a predictable operational expense, one that is willingly accepted as an integral part of owning such a magnificent machine. It is a cost that underscores the potency under the hood, a small price to pay for the symphony of that V8 and the thrill it delivers on every journey.

Real-world expectations

In real-world driving scenarios, the 2025 AMG SL55’s fuel economy can be quite variable, largely dependent on the driver’s right foot and chosen driving style. Owners of all Mercedes Benz fuel economy data vehicles, especially AMG models, seldom purchase them with the primary goal of hypermiling. Instead, they buy them to extract the full measure of performance, to hear the bark of the exhaust, and to feel the thrust of 577 horsepower. Aggressive driving, frequent use of the Sport+ driving mode, and spirited acceleration will inevitably push real-world MPG figures closer to, or even below, the 13 MPG city rating. Conversely, a disciplined driver on a long highway cruise, using the Comfort mode and adaptive cruise control, might even briefly exceed the 21 MPG highway estimate. The engine’s capability for cylinder deactivation, when conditions allow, also plays a subtle role in improving efficiency during light-load cruising. Ultimately, this is a vehicle for those who prioritize exhilaration and engagement over pure economy, understanding that the powerful 4.0L V8, while capable of some efficiency on the highway, is truly designed to deliver unadulterated performance.

How it compares

When placed against its competitive set, the 2025 AMG SL55’s fuel economy figures are squarely in line with what one expects from a high-performance luxury roadster. Consider key rivals: the Porsche 911 Carrera S Cabriolet (3.0L twin-turbo flat-six, 443 hp) typically achieves 18 MPG combined, with 17 city and 23 highway. The Aston Martin Vantage Roadster (4.0L twin-turbo V8, 503 hp) comes in at a similar 17 MPG combined, with 15 city and 22 highway. Even the BMW M850i Convertible (4.4L twin-turbo V8, 523 hp), arguably a softer grand tourer, manages 19 MPG combined, with 17 city and 24 highway. These are all vehicles within a similar performance and luxury envelope, and their fuel efficiency numbers cluster tightly. The SL55’s 16 MPG combined is entirely competitive, especially given its potent 577-horsepower output and its standard 4MATIC+ all-wheel-drive system, which often carries a minor efficiency penalty compared to a rear-wheel-drive setup. Buyers of these vehicles are cross-shopping performance, brand prestige, interior luxury, and sonic experience, not a few points of MPG. The AMG MPG across all years has consistently reflected this balance of power and (relative) efficiency.

Tips to maximize efficiency

While the AMG SL55 is not about maximizing economy, even its owners can adopt practices to make the most of every gallon. Engaging Comfort mode rather than the more aggressive Sport or Sport+ settings will soften throttle response, optimize transmission shift points for smoothness and efficiency, and reduce overall engine strain.

Anticipate traffic flow and avoid hard acceleration or braking. Smooth, gradual inputs not only improve ride comfort but also prevent the turbos from spooling up unnecessarily, helping the V8 consume fuel more sparingly.

On long highway stretches, use the adaptive cruise control system. It can maintain a consistent speed more efficiently than a human foot, especially when dealing with slight elevation changes or variable traffic.

Ensure your tires are properly inflated to the manufacturer’s recommended pressures. Underinflated tires increase rolling resistance, forcing the engine to work harder and reducing overall fuel economy without any performance benefit.

Limit unnecessary weight in the trunk and on the passenger seat. While the SL55 is not a large vehicle, every extra pound requires more energy to move, influencing its fuel consumption over time.