25 MPG combined is what you can expect for open-air thrills in the 2025 BMW Z4 M40i. No one buys this car to hypermile. They buy it for the sound of the inline-six engine, the sharp handling, and the wind-in-your-hair experience. The fuel economy is simply a background consideration, a reality accepted in exchange for the Z4’s distinctive character. Prospective owners are less concerned with squeezing every last mile from a gallon and more focused on the immediate gratification of a well-executed apex or the confident surge of torque on an open road. It’s a trade-off most are willing to make, and one that BMW has carefully calibrated to deliver performance without excessive penalty.

City and highway performance

The EPA estimates peg city driving at 23 MPG and highway cruising at 29 MPG. The discrepancy, while present, is less pronounced than in some performance vehicles. The Z4’s turbocharged engine with electric motor management and smooth-shifting eight-speed automatic transmission (S8) minimize fuel consumption even in stop-and-go conditions. Out on the open road, the 29 MPG figure is easily achievable, provided you resist the urge to constantly dip into the M40i’s considerable power reserves. But let’s be honest, that’s a challenge most drivers will happily fail.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2025 BMW Z4 M40i at $2,300. This figure is based on driving 15,000 miles per year and assumes a national average fuel price. Whether you exceed or fall below that number will obviously influence your individual costs. The M40i requires premium fuel, which contributes to the higher annual figure, but it is a necessary element to achieving the advertised horsepower and torque figures. Considering the performance, $2,300 can be considered a reasonable expense for the enjoyment the car provides.

Real-world expectations

EPA ratings are a useful benchmark, but real-world fuel economy often deviates. Aggressive driving, traffic congestion, and even something as simple as tire pressure can impact how many miles you get per gallon. Z4 M40i drivers indulging in the car’s performance capabilities should anticipate numbers closer to the low end of the EPA range, potentially dipping slightly below 23 MPG in mixed driving. Conversely, those who prioritize fuel efficiency on longer journeys could potentially see figures exceeding the 29 MPG highway estimate. The key is understanding that your personal driving style will ultimately determine your actual fuel consumption.

How it compares

The BMW Z4 M40i occupies a specific niche: a two-seat convertible with genuine performance credentials. Comparing it to other roadsters reveals some interesting contrasts. The Porsche 718 Boxster, for instance, achieves around 24 MPG combined in base form, with the more potent GTS 4.0 models landing nearer to 20 MPG. The Audi TT Roadster, another stylish convertible, manages slightly better numbers in its base configuration, around 26 MPG combined, but it lacks the Z4’s raw power. Even within the BMW family, you can find alternate economy numbers. You’ll see all Bmw fuel economy data listed together. Fuel economy seldom tops the list of priorities for buyers in this segment. The Z4 M40i offers a blend of performance and relative efficiency compared to its direct competitors, though each presents distinct benefits in terms of handling, style, and prestige. To explore Z4 MPG across all years, see our other data.

Tips to maximize efficiency

Engage “Eco Pro” mode whenever possible, especially on longer highway stretches. This mode adjusts throttle response and shift patterns to prioritize fuel efficiency, making a noticeable difference without completely neutering the car’s character. If you know you’ll encounter slow, stop-and-go traffic, this mode becomes essential for combating fuel drain.

Regularly check your tire pressure and ensure it matches the recommended levels listed on the doorjamb. Underinflated tires increase rolling resistance, directly impacting fuel consumption. Consistent monitoring also promotes even tire wear, extending the lifespan of your performance tires.

Avoid excessive idling. Even a few minutes of idling can waste a significant amount of fuel, especially with a reliable engine like the M40i’s inline-six. If you anticipate a wait of more than 30 seconds, simply turn off the ignition.

Plan your routes strategically. Avoiding peak traffic times and construction zones can significantly improve fuel economy by minimizing stop-and-go driving. Use navigation apps to identify the most efficient routes, even if they are slightly longer in distance.

Resist the temptation to constantly accelerate aggressively. The Z4 M40i’s engine is responsive and rewarding, but frequent bursts of acceleration consume fuel at an alarming rate. Smooth, progressive acceleration is key to maximizing efficiency without sacrificing driving pleasure.