24 MPG combined isn’t going to win any eco-awards, but it’s a perfectly respectable figure for the 2018 Porsche 911 Carrera 4S Cabriolet. Let’s be honest: nobody buys this car for its outstanding fuel efficiency. They buy it for the visceral thrill of open-top motoring, the legendary 911 handling, and the unmistakable sound of a flat-six engine singing behind their heads. The fuel consumption is simply a necessary compromise.

City and highway performance

The EPA estimates for the 2018 911 Carrera 4S Cabriolet peg city driving at 21 MPG and highway cruising at 28 MPG. Predictably, the city figure takes a hit due to frequent stops and starts, and the inherent inefficiency of any internal combustion engine when accelerating from a standstill. The highway number, however, reflects the car’s ability to settle into a relatively efficient cruising speed. The seven-speed PDK automatic transmission (officially designated AM-S7 by the EPA) plays a key role here, keeping the engine in the optimal part of its powerband for efficiency. Owners who spend a significant amount of time on the open road will likely see fuel economy closer to that 28 MPG figure, while primarily city dwellers should expect results nearer the 21 MPG mark.

Annual fuel cost

The EPA calculates the annual fuel cost for the 2018 Porsche 911 Carrera 4S Cabriolet at $2,400. This figure is based on driving 15,000 miles per year, using the EPA’s combined MPG estimate and prevailing national average fuel prices. Of course, your actual fuel costs will vary depending on how much you drive, where you drive, and the ever-fluctuating price of gasoline. Drivers with a heavier foot or those who frequently exercise the 911’s performance capabilities will undoubtedly exceed this estimate. If you’re considering a vehicle of this caliber, fuel costs are likely a secondary consideration, but it’s good to be aware of the potential expense.

Real-world expectations

While the EPA estimates provide a standardized benchmark, real-world fuel economy often differs. Factors such as driving style, traffic conditions, road grade, and even tire pressure can all influence fuel consumption. Owners who prioritize spirited driving will naturally see lower numbers than those who adopt a more conservative approach. Ambient temperature can also play a role; cold weather typically reduces fuel efficiency as engines require more fuel to reach optimal operating temperatures. Expect to see slight variations around the EPA estimates, but generally within a reasonable margin.

How it compares

Compared to other performance convertibles, the 2018 Porsche 911 Carrera 4S Cabriolet holds its own in terms of fuel economy. A BMW M4 Convertible, for example, achieves a combined 19 MPG. The Mercedes-AMG C 63 S Cabriolet boasts an even lower 18 MPG combined. Even all all Porsche fuel economy data including other older 911 variants can be worse than the 2018 4S Cabriolet. Opting for the standard Carrera Cabriolet with rear-wheel drive and the PDK also bumps the combined MPG to 24, although this is still not a tremendous amount. This highlights that even within the performance car segment, and even within the 911 MPG across all years range, the Porsche manages to strike a balance between performance and relative efficiency. This comparison matters because while buyers aren’t solely prioritizing fuel economy, they are still conscientious about getting reasonable mileage, given the investment.

Tips to maximize efficiency

While this car is built for speed, there are still ways to improve its efficiency. Avoid aggressive acceleration and hard braking. Smooth, progressive throttle inputs are key to minimizing fuel consumption, even in a 911. Treat every stop light like an exercise in efficiency and see if you can stay under 3,000 RPM from a standstill.

Ensure your tires are properly inflated to the manufacturer’s recommended pressure. Underinflated tires increase rolling resistance, leading to decreased fuel economy. Check your tire pressure regularly, especially during seasonal temperature changes.

Consider using the “Normal” driving mode when conditions allow. The 911’s driving mode selector alters various parameters, including throttle response and shift points. The “Normal” mode prioritizes fuel efficiency over outright performance.

Reduce unnecessary weight. Carrying excessive cargo adds to the vehicle’s load, impacting fuel economy. Remove any unnecessary items from the trunk and passenger compartment.

Plan your routes to avoid heavy traffic and congestion. Stop-and-go driving significantly reduces fuel efficiency. Use navigation apps to identify and circumvent traffic bottlenecks.