Sixteen miles per gallon combined is the price of entry for a handcrafted, twin-turbocharged V12 under the sculpted hood of a 2018 Mercedes-Benz AMG SL65. This isn’t a car bought by people who meticulously track every gallon consumed; it’s a statement of power, luxury, and exclusivity, where fuel economy is a distant afterthought.

City and highway performance

The EPA estimates the SL65 AMG achieves 13 MPG in the city and 22 MPG on the highway. While these numbers are certainly low compared to almost every other vehicle on the road today, they are somewhat respectable when you consider the sheer displacement and output of the 6.0-liter engine. The city figure reflects the significant fuel consumption required to repeatedly accelerate over 4,300 pounds of German engineering. The highway number, while still underwhelming, demonstrates that the engine is capable of operating relatively efficiently once cruising at a steady state, using the 7-speed automatic transmission to keep the engine in its most efficient rev range.

Annual fuel cost

The EPA estimates that the annual fuel cost for the 2018 Mercedes-Benz AMG SL65 will be approximately $3,600. This figure is based on driving 15,000 miles per year and using national average fuel prices. Premium fuel is required for optimal performance and longevity of the engine, and using regular fuel can potentially damage the engine. Therefore, it can be reasonably assumed that this price will be much higher for the majority of owners.

Real-world expectations

Don’t expect to consistently achieve even the EPA’s modest figures in real-world driving. If you spend most of your time in city traffic, aggressively using the available power, or frequently indulging in full-throttle acceleration runs, expect the MPG to dip well below 13. Conversely, if you primarily use the SL65 for long highway trips at moderate speeds, it’s possible to approach, or even slightly exceed, the 22 MPG highway estimate. However, given the intoxicating nature of this engine, resisting the urge to tap into its immense power on occasion is a difficult task.

How it compares

Compared to other high-performance roadsters, the SL65 AMG’s fuel economy is towards the bottom end of the scale. For example, the Mercedes-Benz AMG GT C Roadster, with its smaller 4.0-liter V8, achieves 16 MPG city and 22 MPG highway, matching the SL65 on the highway but offering a notable improvement in city driving. Even the Porsche 911 Turbo S Cabriolet, with its blistering performance, manages around 19 MPG combined. This isn’t to say that the SL65 is inherently inefficient; it simply reflects the cost of its specific powertrain and the type of performance it delivers. When looking at all Mercedes Benz fuel economy data, you realize that the SL65’s numbers are the exception and not the rule. However, those considering the SL65 are typically more concerned with the experience it provides than with getting every last mile out of each gallon of fuel. Consider all AMG MPG across all years and you will find some other vehicles as thirsty as this one.

Tips to maximize efficiency

While fuel economy might not be a primary concern for SL65 owners, there are still ways to mildly improve efficiency without sacrificing too much enjoyment. Reduce unnecessary idling, as this car consumes much more fuel while stationary than a typical compact sedan. Avoid prolonged warm-up periods, allowing the car to reach operating temperature while driving gently.

Proper tire inflation is critical for both safety and fuel economy. Check your tire pressures regularly and ensure they are at the recommended levels. Low tire pressure increases rolling resistance, which negatively impacts fuel efficiency.

Be mindful of your driving style. While the temptation to unleash the full potential of the V12 is strong, doing so frequently will severely impact fuel consumption. Practicing smooth acceleration and braking can make a noticeable difference over time.

Ensure that the vehicle is properly maintained. Regular maintenance, including oil changes, air filter replacements, and spark plug inspections, helps the engine run efficiently.