The 2020 Mercedes-Benz SL550 gets an EPA-estimated 20 MPG combined. It’s not intended to be a leader in fuel efficiency. The SL550 is a grand touring roadster, engineered for performance and luxurious open-air motoring, not for maximizing miles per gallon. Its buyers are typically affluent enthusiasts who prioritize driving experience over outright fuel efficiency.

City and highway performance

The EPA rates the SL550’s 4.7-liter twin-turbo V8 at 17 MPG in the city and 25 MPG on the highway. The city figure reflects stop-and-go traffic, where the SL550’s weight and powerful engine use more fuel. The highway number shows what’s possible when cruising at a steady speed, with the nine-speed automatic transmission helping to keep the revs low. The transmission is critical for fuel efficiency, allowing the engine to operate efficiently.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2020 Mercedes-Benz SL550 to be $2,900. This is based on driving 15,000 miles per year and using national average fuel prices. This number can vary significantly depending on driving habits, location, and the cost of gasoline. Drivers who mostly drive in the city or accelerate quickly will likely exceed this estimate. The EPA’s estimate assumes a certain percentage of city versus highway driving, influencing the final figure.

Real-world expectations

Real-world fuel economy often differs from the EPA estimates. How you drive heavily influences the SL550’s fuel consumption. Accelerating quickly and frequently using the engine’s power will decrease fuel efficiency. A more relaxed driving style, prioritizing smooth acceleration and maintaining consistent speeds, can improve fuel economy closer to the EPA estimates. Terrain also plays a role. Hilly or mountainous routes will likely decrease fuel economy compared to flat highways. Watch the instantaneous fuel economy display to identify ways to reduce fuel consumption.

How it compares

The SL550’s fuel economy is similar to other high-performance luxury roadsters, but specific comparisons are important. The BMW Z4 M40i, for example, offers similar performance but achieves a slightly better combined rating of 25 MPG thanks to its smaller engine and lighter weight. The Porsche 911 Carrera Cabriolet, another competitor, manages around 20 MPG combined, closely matching the SL550, although some trims offer slightly better fuel economy. For buyers considering other Mercedes Benz options, all Mercedes Benz fuel economy data shows there are far more efficient options in the lineup. Those wanting more information about the 4.7L turbocharged V8 can research the SL550 MPG across all years it was available.

Tips to maximize efficiency

Proper tire inflation is important for optimal fuel economy. Underinflated tires increase rolling resistance, forcing the engine to work harder. Check your tire pressures regularly and inflate them to the recommended level, typically found on a sticker inside the driver’s side door jamb. Even a small difference can affect fuel consumption over time.

Avoid unnecessary idling. If you’re stopped for more than a minute, turn off the engine. Modern engines are designed to restart quickly and efficiently, and idling consumes fuel without any benefit. This is especially relevant in urban environments where traffic congestion is common.

Use cruise control on the highway whenever possible. Maintaining a consistent speed can significantly improve fuel economy. Cruise control minimizes changes in speed, preventing unnecessary acceleration and deceleration that waste fuel. Plan your route in advance to avoid areas with frequent speed changes.

Minimize excessive acceleration. Smooth, gradual acceleration is more fuel-efficient than rapid starts. The SL550’s powerful engine can make it tempting to accelerate quickly, but resisting this urge will save fuel. Anticipate traffic flow and adjust your speed accordingly to avoid abrupt acceleration and braking.