21 MPG combined isn’t going to break any records, but for the 2015 Porsche 911 Carrera GTS Cabriolet 3.8L, it’s quite respectable. This isn’t a car for commuting, it’s a visceral, high-performance machine designed to deliver an unparalleled driving experience. No one buys a GTS Cabriolet expecting Prius-like fuel economy. They buy it for the sound, the speed, and the open-air thrill. The fuel consumption is simply the price of admission.

City and highway performance

The EPA estimates for the 2015 911 Carrera GTS Cabriolet break down to 19 MPG in the city and 25 MPG on the highway. The city figure reflects the stop-and-go nature of urban driving, and is affected by a heavy right foot. The 3.8-liter flat-six encourages spirited acceleration, so expect that number to trend downward if you frequently unleash all 430 horsepower. On the open road, the 25 MPG highway figure is more attainable, particularly when using cruise control and resisting the urge to overtake every car. The PDK dual-clutch transmission also contributes to highway efficiency, shifting easily and quickly to keep the engine in its optimal rev range.

Annual fuel cost

According to the EPA, the estimated annual fuel cost for the 2015 Porsche 911 Carrera GTS Cabriolet is $2,750. This figure is based on driving 15,000 miles per year and using national average fuel prices for premium gasoline, which this Porsche requires. Fuel prices fluctuate, so this number is likely to change over time. If you drive more or less than 15,000 miles annually, your fuel costs will vary. The $2,750 estimate provides a reasonable benchmark for budgeting.

Real-world expectations

While the EPA estimates provide a useful baseline, real-world fuel economy often differs. Driving style, traffic conditions, and tire pressures can impact fuel consumption. Owners who prioritize performance and regularly explore the upper reaches of the rev range will likely see figures lower than the EPA estimates. However, those who adopt a more relaxed driving style and spend more time on the highway may achieve slightly better fuel economy. Expect to see numbers within a few MPG of the EPA ratings, but don’t be surprised if your fuel economy varies depending on how and where you drive the car. You can explore 911 MPG across all years to see how this generation compares.

How it compares

Compared to other high-performance convertibles, the 2015 911 Carrera GTS Cabriolet’s fuel economy is generally in line with its competitors. For comparison, the BMW M4 Convertible with its 3.0-liter turbocharged engine gets around 19 MPG combined. The Chevrolet Corvette Stingray Convertible, with its 6.2-liter V8, achieves a similar 19 MPG combined rating, but can achieve up to 27 mpg on the highway in the best conditions. Even within the Porsche family, the base 911 Carrera Cabriolet with the 3.4-liter engine gets 22 MPG combined, only slightly better than the GTS. These figures show that performance comes at a cost. Buyers considering a GTS likely aren’t cross-shopping with economy cars, they’re weighing the exhilaration against the expense, and for many, the GTS offers a good blend of performance and relative efficiency in this segment. You can find all Porsche fuel economy data on our site.

Tips to maximize efficiency

While the 2015 911 Carrera GTS Cabriolet isn’t designed to be a fuel-sipping commuter, there are ways to improve its efficiency. Avoid aggressive acceleration and braking, which consume excessive amounts of fuel. Smooth, gradual inputs will help to keep the engine in its most efficient operating range. Using cruise control on the highway can help maintain a consistent speed and reduce fuel consumption.

Ensure that your tires are properly inflated. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressures regularly and inflate them to the recommended levels. Consider your driving routes. Avoiding stop-and-go traffic and choosing routes with fewer hills can also help to improve fuel economy.

Regular maintenance is important for optimal performance and efficiency. Ensure that your engine is properly tuned and that all filters are clean. A well-maintained engine will run more efficiently and consume less fuel. Minimize excessive idling. Idling consumes fuel without moving the car, so turn off the engine whenever you’re stopped for more than a minute or two.

Finally, consider using the Sport or Sport Plus modes sparingly. While these modes enhance throttle response and sharpen handling, they also tend to decrease fuel economy. Save these modes for spirited driving when you want to fully exploit the car’s performance capabilities while being mindful of their impact on fuel consumption.