21 MPG combined is a figure few prospective 2025 Porsche 718 Boxster GTS 4.0 buyers will even register, let alone use as a primary purchasing criterion. This is a car bought for the singular, intoxicating wail of a naturally aspirated flat-six engine mounted just behind the seats, for the surgical precision of its steering, and for the unfiltered communication it delivers to the driver. Fuel economy, while certainly a consideration for any vehicle, is an asterisk on the spec sheet of a car designed almost exclusively for driving pleasure and track day exhilaration.

City and highway performance

The EPA rates the 718 Boxster GTS 4.0 at 19 MPG in the city and 24 MPG on the highway with its Automatic (AM-S7) transmission. These numbers represent the expected split for a high-performance, naturally aspirated engine. Stop-and-go city driving, where the 4.0L six-cylinder is often held in lower gears and subjected to frequent acceleration and braking, naturally dips into the fuel tank more readily. The engine’s inherent thirst for revs, a characteristic so central to its appeal, means that city driving rarely allows it to settle into its most efficient operating range.

On the open highway, however, the picture improves. At cruising speeds, the seven-speed Porsche Doppelkupplung (PDK) transmission, designated AM-S7 by the EPA, can slot into its highest gears, allowing the engine to turn at significantly lower RPMs. This is where the GTS 4.0 achieves its 24 MPG highway figure. While some might expect more from a modern powertrain, the GTS 4.0 isn’t designed to sip fuel, it’s engineered to deliver an uncompromised sports car experience. The relatively compact footprint and impressive aerodynamic efficiency of the Boxster chassis certainly help mitigate some of the engine’s inherent hunger for premium unleaded, but ultimately, the priority here is performance, not parsimony.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,750 for the 2025 Porsche 718 Boxster GTS 4.0. This figure, critical for understanding the vehicle’s running expenses, is calculated based on an assumed 15,000 miles of driving per year, split between city and highway conditions, and using national average fuel prices. For a car like the Boxster GTS 4.0, which frequently sees spirited driving or track use, this $2,750 figure represents a baseline. Owners who regularly exploit the 8,000 RPM redline or participate in track days will undoubtedly incur higher annual fuel expenses. However, for a buyer contemplating a six-figure roadster, the annual fuel cost is typically a minor line item in the overall budget, often overshadowed by insurance, maintenance, and depreciation.

Real-world expectations

In real-world driving, owners of the 2025 718 Boxster GTS 4.0 should expect to see fuel economy figures closely mirroring, or slightly below, the EPA estimates. The 4.0-liter naturally aspirated flat-six is an enthusiast’s engine, it rewards high revs and aggressive throttle inputs with an intoxicating soundtrack and relentless acceleration. Few drivers will purchase this particular Boxster variant to commute placidly. The temptation to exploit the engine’s full range of capabilities is almost irresistible, and doing so will inevitably consume more fuel. Regular excursions on open country roads, canyon carving, or track events will push fuel consumption closer to the city rating, or even lower, depending on the intensity of the driving. Even when driven conservatively, the engine’s displacement and design mean it will always be more fuel-intensive than, say, a turbocharged 2.0-liter four-cylinder alternative. This is a compromise willingly accepted by its target audience, who prioritize the visceral experience above all else.

How it compares

Comparing the 718 Boxster GTS 4.0’s fuel economy is best done within its specific niche of high-performance roadsters and sports cars, particularly those with a focus on naturally aspirated engines. Let’s look at a few relevant examples:

The all Porsche fuel economy data shows that even other Porsche models, such as the 911 Carrera S with its twin-turbo 3.0L flat-six, often achieve slightly better numbers, typically around 20 MPG city / 26 MPG highway. The Boxster GTS 4.0 is a specialized machine. Directly comparing it to less performance-oriented convertibles would be a disservice to its mission. For example, a BMW Z4 M40i, with its turbocharged inline-six, boasts a superior 23 MPG city / 30 MPG highway, but the character of the engine and the driving experience are fundamentally different. The Z4 focuses more on effortless torque and grand touring comfort, while the Boxster GTS is an unashamed sports car.

Even within the 718 family, the GTS 4.0 stands apart. The base 718 Boxster with its 2.0-liter turbo-four delivers a much more efficient 21 MPG city / 27 MPG highway. The 718 Boxster S, with its 2.5-liter turbo-four, slots in at 21 MPG city / 27 MPG highway. This demonstrates that the naturally aspirated 4.0-liter engine, while delivering an entirely different auditory and tactile experience, does come with an expected fuel economy penalty. The buyer choosing the GTS 4.0 understands this trade-off completely, they are buying the engine, the sound, and the linear power delivery that only a naturally aspirated powerplant can provide. They are not chasing the absolute highest MPG figures, but rather the purest driving sensation. For more information on 718 MPG across all years, our database provides data.

Tips to maximize efficiency

While maximizing fuel economy isn’t the primary goal for a 2025 Boxster GTS 4.0 owner, there are still techniques to adopt if you want to extend your range or simply be more mindful of consumption during daily driving. Smooth, gradual inputs are key, avoid abrupt acceleration and braking whenever possible. Allowing the PDK transmission to shift early and keep the engine in higher gears will significantly reduce fuel burn, particularly in city or suburban driving.

Maintaining proper tire pressure is a simple yet effective way to ensure your car is operating at its peak efficiency. Underinflated tires increase rolling resistance, forcing the engine to work harder. Regularly check your tire pressures, especially before longer drives, to keep them at the manufacturer’s recommended levels.

Minimize unnecessary weight in the vehicle. While the Boxster is an inherently light car, removing any heavy items from the frunk or trunk that aren’t needed for your journey can contribute to slight improvements in fuel economy. Every little bit of extra mass the engine has to move requires more fuel.

Use the car’s Sport mode judiciously. While Sport mode sharpens throttle response and holds gears longer, which is fantastic for performance driving, it’s detrimental to fuel economy during relaxed cruising. Stick to Normal mode for everyday driving to allow the PDK to optimize for efficiency.