21 MPG combined for the 2025 Porsche 718 Cayman GTS 4.0L with the automatic transmission is not simply a number; it’s a necessary characteristic for a vehicle designed to relentlessly pursue driving purity. This isn’t a family hauler or a daily commuter for the mileage-obsessed. It’s an unadulterated sports car, a precision instrument crafted for those who prioritize immediate throttle response, the visceral thrill of a naturally aspirated flat-six engine screaming to its 8,000 RPM redline, and telepathic handling above all else. The buyer of a Cayman GTS 4.0 understands that fuel economy is a secondary consideration, a necessary characteristic of a machine that delivers unparalleled engagement. They are individuals who relish the journey as much as the destination, and for whom the symphony from behind the seats is worth every gallon of premium unleaded.

City and highway performance

Looking at the EPA’s figures, the 718 Cayman GTS 4.0 achieves 19 MPG in city driving and 24 MPG on the highway. In urban environments, the 4.0-liter naturally aspirated flat-six, even with its cylinder deactivation technology, is still a large displacement engine revving through its ratios. Stop-and-go traffic inevitably consumes more fuel as the powertrain works to get nearly 3,200 pounds of meticulously engineered German metal moving again and again. The precise, quick-shifting PDK automatic transmission helps mitigate some of this, ensuring optimal gear selections, but physics remains undefeated. On the open road, the 24 MPG highway figure is respectable for a vehicle of this performance caliber. Cruising at highway speeds, the engine settles into its most efficient operating zones, and the aerodynamic slipperiness of the Cayman’s purposeful design comes to the forefront. However, anyone who drives a Cayman GTS 4.0 realistically knows that sustained, fuel-sipping highway cruising is rarely its ultimate purpose. This car begs to be driven dynamically, and spirited driving will always see those numbers dip.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,750 for the 2025 Porsche 718 Cayman GTS 4.0L. This figure is derived assuming 15,000 miles of driving per year, split between city and highway conditions (45% city, 55% highway), and using national average fuel prices for premium gasoline. For the typical Cayman GTS owner, this cost is a negligible consideration within the larger financial commitment of purchasing and maintaining such a finely tuned machine. The initial outlay, insurance, and routine maintenance for a high-performance Porsche far eclipse the annual fuel bill. This $2,750 represents the cost of feeding a passion, not a burden. It’s the tariff for accessing one of the last, great naturally aspirated internal combustion engines available in a contemporary sports car, a small price for an automotive experience that is rapidly becoming a relic.

Real-world expectations

In the real world, the fuel economy of the 718 Cayman GTS 4.0 is highly dependent on driving style. For the owner who frequently explores the upper reaches of the tachometer, reveling in the flat-six’s glorious soundtrack, 19-24 MPG will likely be optimistic. Enthusiastic canyon carving or track days will see single-digit MPG figures, a direct consequence of harnessing all 394 horsepower. Conversely, owners who use their Cayman for occasional relaxed commutes or extended highway trips might indeed see the EPA’s numbers, or even slightly exceed them on a long, steady cruise. Owners of this particular 718 don’t typically baby the accelerator. The very essence of the GTS 4.0 is its responsiveness and its ability to connect the driver directly to the road. Sacrificing fuel economy for the unparalleled driving enjoyment it provides is not merely accepted; it’s understood as part of the car’s DNA. Anyone considering this vehicle knows that its mission is performance, not parsimony. For more on the brand’s efficiency, see all Porsche fuel economy data.

How it compares

When placed against its direct competitors, the 718 Cayman GTS 4.0’s fuel economy figures are right in line with expectations for its segment and powertrain. A BMW M2 Coupe, with its 3.0-liter twin-turbo inline-six, achieves 19 MPG combined (16 city / 23 highway) with its automatic transmission. The Toyota Supra 3.0, sharing its powertrain with BMW, sees similar numbers at 24 MPG combined (23 city / 31 highway) which is surprisingly strong. Even the slightly larger and more luxurious Corvette Stingray, with its mighty 6.2-liter V8, manages a very respectable 19 MPG combined (16 city / 24 highway) with its 8-speed automatic. These comparisons highlight that the Cayman GTS 4.0, with its naturally aspirated engine and performance focus, isn’t an outlier. Its fuel consumption is typical for a compact, high-performance sports car from a premium manufacturer. Buyers aren’t cross-shopping against hybrids; they’re looking for driver engagement, and the GTS 4.0 delivers. For a deeper dive into model year statistics, check out the 718 MPG across all years.

Tips to maximize efficiency

While fuel efficiency isn’t the primary concern for most 718 Cayman GTS 4.0 owners, there are still ways to optimize consumption when desired. Smooth and progressive throttle inputs, avoiding abrupt acceleration and braking, will invariably yield better mileage, as the flat-six won’t be pushed into its higher, thirstier RPM ranges as frequently. Using the car’s different drive modes can also help. While Sport and Sport Plus modes sharpen throttle response and hold gears longer, Normal mode allows for earlier upshifts and more relaxed engine behavior, beneficial for cruising. Maintaining proper tire pressure is a simple yet effective way to ensure the car rolls with minimal resistance, directly impacting fuel use. Avoiding carrying unnecessary weight in the frunk or trunk, though arguably minor, can also contribute to reducing the engine’s workload. Regular maintenance, including oil changes and air filter replacements, ensures the engine is always operating at its peak efficiency, combusting fuel as cleanly and completely as possible.