16 MPG combined. Frankly, fuel consumption isn’t a major concern for those spending six figures on a hand-built AMG SL55 roadster. It’s about the visceral experience of a twin-turbocharged V8 under a long, sculpted hood. The SL55 is a statement of raw performance and luxurious open-air motoring, making the fuel gauge a relatively minor detail for its target audience.

City and highway performance

The AMG SL55 isn’t fuel-efficient in any driving situation. Its 14 MPG city rating reflects the reality of navigating urban environments in a performance car. Stop-and-go traffic, frequent acceleration, and the inherent nature of a large engine all contribute. The SL55 fares slightly better on the open road, achieving 21 MPG on the highway. While an improvement, it’s hardly class-leading, and spirited driving will quickly reduce even this modest efficiency. This car is for quick bursts of speed, not fuel-saving competitions.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2024 Mercedes-Benz AMG SL55 4matic Plus at $3,600. This is based on driving 15,000 miles per year, with a specific percentage for city and highway driving, using the national average fuel price for premium gasoline at calculation time. This is only an estimate, your actual fuel expenses will vary depending on your driving habits, road types, and fuel prices. Expect to exceed this annual cost if you drive more aggressively or cover significantly more miles than the EPA’s benchmark. Check out all Mercedes Benz fuel economy data to see how costs compare.

Real-world expectations

Don’t expect to consistently match the EPA’s estimates. The AMG SL55’s fuel economy depends heavily on driving style. Fuel economy drops dramatically when you use the car’s power. The 9-speed automatic transmission is designed for rapid gear changes, not to conserve fuel, although it does try to maximize efficiency. Owners who prioritize performance will likely see average MPG figures near the lower end of the EPA’s range, perhaps even below it. Those who drive gently might see 1-2 MPG better on the highway, or 1 MPG in the city.

How it compares

The AMG SL55 exists in a small group of high-performance roadsters, but its fuel economy trails some competitors. The Porsche 911 Carrera S Cabriolet manages around 20 MPG combined, though it isn’t directly comparable overall. The BMW Z4 M40i offers similar thrills with around 26 MPG on the highway. Even within Mercedes-Benz, the AMG C63 S E Performance uses hybrid technology to achieve a much better combined MPG, even though it has a different body style. The SL55 buyer knows these differences but wants the specific blend of performance and luxury the SL offers, accepting the fuel economy trade-off. Compare this to AMG MPG across all years to understand relative efficiency within the sports car landscape.

Tips to maximize efficiency

The AMG SL55 isn’t designed for fuel efficiency, but you can still reduce its thirst. Smooth acceleration and braking can make a difference, as can anticipating traffic to avoid stops and starts. The SL55 has driving modes, including a Comfort mode that prioritizes fuel efficiency by softening throttle response and shifting to higher gears earlier. Use this mode when cruising at steady speeds on the highway.

Regular maintenance is important for fuel economy. Ensure your tires are inflated properly, as underinflated tires increase rolling resistance and reduce MPG. Keep the engine tuned and follow service intervals to prevent performance issues impacting fuel efficiency.

Avoid using Sport and Sport+ driving modes unless seeking maximum performance. These modes significantly alter the powertrain, resulting in more aggressive throttle response and higher engine speeds, inevitably increasing fuel consumption.

Reduce unnecessary weight in the vehicle. Removing extra cargo from the trunk can modestly improve fuel economy, as a lighter car requires less energy to accelerate and maintain speed.