20 MPG combined is what you get for open-air thrills in the 2021 Porsche 911 Carrera 4S Cabriolet. No one buys this car expecting Prius-like efficiency. They buy it for the explosive power, the iconic look, and the wind-in-your-hair experience. The fuel economy is simply a variable they’re willing to accept to own one of the world’s most desirable sports cars.

City and highway performance

The EPA estimates the 2021 911 Carrera 4S Cabriolet achieves 18 MPG in the city and 23 MPG on the highway. The city figure reflects stop-and-go driving, where the turbocharged 3.0-liter flat-six engine works harder and the eight-speed PDK automatic shifts gears frequently. Highway mileage is better, benefiting from the transmission’s ability to settle into higher gears and the engine’s efficiency at cruising speeds. These numbers depend on driving style, a heavy foot will drastically reduce fuel economy.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 Porsche 911 Carrera 4S Cabriolet at $2,900. This is based on driving 15,000 miles per year and using national average fuel prices (which fluctuate, impacting the real-world cost). The figure provides a benchmark for budgeting, but individual spending will vary depending on driving habits and local fuel costs.

Real-world expectations

Drivers who frequently push the 911’s performance should expect fuel economy to dip below the EPA estimates. Hard acceleration, aggressive cornering, and extended time in Sport mode will all affect it. Owners who drive smoothly and use the automatic start/stop system can potentially achieve figures closer to, or even slightly above, the EPA ratings. It requires restraint and a conscious effort to drive efficiently, something that might be challenging.

How it compares

The Porsche 911 exists where performance often trumps pure efficiency, but looking at competitors provides context. The BMW M4 Competition Convertible, with its 3.0L inline-six, manages a similar 16 MPG city and 23 MPG highway. The Mercedes-AMG C63 S Cabriolet, packing a potent 4.0L V8, lands at 17 MPG city and 26 MPG highway. Even the Audi R8 Spyder, a V10-powered supercar, achieves a comparable 13 MPG city and 20 MPG Highway. These comparisons show where the 911 falls and underscore that this level of performance comes with a fuel economy penalty. Comparing 911 MPG across all years against competitors shows that the 992 generation is very competitive.

Tips to maximize efficiency

Resist the urge to constantly explore the upper reaches of the tachometer. The 911’s engine produces ample torque at lower RPMs, allowing for quick acceleration without needing to push it to the redline. Smooth throttle inputs help save fuel.

Learn the driving modes. The “Normal” mode prioritizes efficiency, optimizing engine and transmission settings for everyday driving. While “Sport” and “Sport Plus” let loose the car’s full potential, they also increase fuel consumption. Use these modes carefully.

Ensure proper tire inflation. Underinflated tires increase rolling resistance, forcing the engine to work harder and reducing fuel economy. Check tire pressure regularly and maintain the recommended levels in the owner’s manual.

Minimize unnecessary weight. Extra cargo adds to the load, decreasing efficiency. Remove any items that are not essential.

Use the automatic start/stop system, which shuts off the engine when the car is stopped. While some drivers find it intrusive, it can save fuel in stop-and-go traffic. Also, consider reviewing all Porsche fuel economy data to learn more about the manufacturer’s efficiency gains.