23 MPG combined is an acceptable figure for the 2017 Mercedes-Benz SL450, and not the reason anyone buys this car. This powerful grand tourer, with its retractable hardtop and undeniable style, is designed for effortless cruising and making a statement. Fuel economy is simply a secondary concern, far behind luxurious features, thrilling performance, and the prestige of Mercedes-Benz.

City and highway performance

The SL450 achieves an EPA-estimated 20 MPG in the city and 28 MPG on the highway. These figures reflect the car’s ability to balance power with reasonable efficiency, thanks to its turbocharged 3.0L V6 engine and smooth-shifting nine-speed automatic transmission. The city MPG is workable for enjoying the SL450’s responsive acceleration around town, while the highway MPG enables comfortable and relatively economical long-distance journeys. It’s a combination that appeals to its target audience: affluent individuals who appreciate open-top motoring and aren’t overly worried about the cost of premium gasoline.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2017 Mercedes-Benz SL450 at $2,500. This calculation assumes 15,000 miles of driving per year, with a 55/45 split between city and highway miles, using the national average fuel price. It’s a useful benchmark, but drivers should remember that their actual fuel costs will vary based on their driving habits, local fuel prices, and the specific type of driving they do. Spirited backroad driving will always result in a higher bill than a long freeway trip.

Real-world expectations

While the EPA provides a standardized estimate, real-world fuel economy will vary. Aggressive driving, frequent short trips, and stop-and-go traffic can all significantly decrease fuel efficiency.

Gentle acceleration, consistent speeds on the open road, and regular maintenance can help drivers achieve numbers closer to, or even slightly exceeding, the EPA estimates. The SL450’s character also plays a part; its power encourages enthusiastic driving, which impacts consumption.

How it compares

Compared to its competitors, the SL450’s fuel economy is similar to expectations for a luxury roadster. The BMW Z4 M40i, for instance, also equipped with a turbocharged inline-six, gets around 25 MPG combined. A Porsche 911 Carrera Cabriolet sees similar numbers, around 21 to 24 MPG combined depending on the model and options. These cars value performance and style, so buyers accept that fuel efficiency isn’t a high priority. Drivers wanting to see all Mercedes Benz fuel economy data can use this resource. For information about SL450 MPG across all years, this tool is a great resource.

Tips to maximize efficiency

While the SL450 isn’t primarily about fuel efficiency, owners can take steps to minimize their consumption. Ensure that the tires are properly inflated to the recommended pressure, as this reduces rolling resistance and improves fuel economy. Regular maintenance, including oil changes and air filter replacements, keeps the engine running optimally.

Avoid aggressive acceleration and hard braking, especially in urban environments. The SL450 has ample power, but smooth driving will conserve fuel. Anticipate traffic flow and maintain a consistent speed whenever possible to avoid unnecessary bursts of acceleration.

Use the car’s driving modes. The “Comfort” or “Eco” modes, if equipped, often adjust the engine and transmission settings to prioritize fuel efficiency. These modes may slightly reduce performance, but they can make a noticeable difference in fuel consumption during everyday driving.

Limit the use of energy-intensive accessories such as air conditioning. Of course, driving with the top down will negate this benefit. However, on cooler days, opting for natural ventilation can save fuel. Even small adjustments can lead to fuel savings over time.