29 MPG combined makes the 2026 BMW M340i Sedan a truly efficient choice for a car that can effortlessly dispatch 0-60 mph in a scant 4.1 seconds. This is not a vehicle built for ultimate fuel frugality, nor does it pretend to be. Instead, 29 MPG represents a balance of power and efficiency, the result of BMW’s engineering prowess, delivering exhilarating performance without completely sacrificing practicality at the pump. This is the enthusiast’s daily driver, the executive’s weekend thrill, a potent blend of luxury and velocity, and its fuel economy figures reflect that deliberate, high-performance compromise.

City and highway performance

The EPA rates the M340i at 27 MPG in the city and 33 MPG on the highway. These numbers are a good benchmark for a 3.0L turbocharged inline-six that produces 382 horsepower and 369 lb-ft of torque. The city figure of 27 MPG is particularly impressive, revealing the efficiency benefits of BMW’s mild-hybrid system, which integrates with the B58 engine and the ZF 8-speed automatic transmission. This synergy allows for smooth start/stop operation and provides subtle electrical assistance in lower speed ranges, mitigating the typical fuel consumption penalties of urban driving for a performance sedan.

On the open road, the 33 MPG highway rating paints a clearer picture of the M340i’s long-distance capabilities. The smooth, torquey inline-six cruises effortlessly at highway speeds, often barely breaching 2,000 RPM thanks to the meticulously geared 8-speed automatic. This efficiency isn’t achieved through sluggishness; far from it. Punch the throttle, and the M340i lunges forward with immediate authority, demonstrating that its highway efficiency is a byproduct of advanced engine design and aerodynamic refinement, not a lack of power. It shows how far internal combustion has come, delivering genuine performance without requiring constant fill-ups on extended journeys.

Annual fuel cost

For the 2026 BMW M340i Sedan, the EPA estimates an annual fuel cost of exactly $2,000. This figure is calculated based on an assumed 15,000 miles of driving per year, with a split of 55% city and 45% highway driving, using national average fuel prices, which are periodically updated by the EPA. It&#8217s a useful benchmark for buyers to understand the average yearly expenditure on fuel. For those considering this particular M340i, this $2,000 annual estimate represents a reasonable expectation for day-to-day driving, factoring in its performance-oriented nature. While individual driving habits and local fuel prices will inevitably cause some variation, this widely understood figure provides a solid foundation for budgeting.

Real-world expectations

In real-world driving scenarios, the M340i often delivers fuel economy very close to its EPA estimates, a hallmark of BMW’s precision engineering. Drivers who routinely engage in spirited driving, frequently exploiting the engine’s full power band, will naturally see figures leaning towards the lower end of the spectrum, possibly dipping into the mid-20s. Conversely, those prioritizing smooth, conservative driving on the highway can comfortably exceed the 33 MPG figure. The mild-hybrid system, while subtle, plays a significant role in maintaining efficiency during stop-and-go traffic, preventing the kind of dramatic drops in city MPG that traditionally plague powerful six-cylinder engines. The beauty of the M340i’s powertrain is its adaptability; it can be incredibly potent or surprisingly efficient, depending entirely on the driver’s intent. M340i MPG across all years tends to show this consistent performance metric.

How it compares

The 2026 BMW M340i exists in a fiercely competitive segment, where performance and efficiency are increasingly intertwined. Its 29 MPG combined rating stands out. The Audi S4, with its 3.0L turbocharged V6, typically achieves around 24-25 MPG combined. The Mercedes-AMG C 43, also with a turbo-six (albeit a 2.0L four-cylinder for 2024 and beyond, expected to carry over to 2026), often registers similar figures in the 24-26 MPG range. Even the Genesis G70 3.3T, a strong value proposition, hovers around 21-22 MPG combined. The BMW M340i truly occupies a unique position for buyers who prioritize premium performance and lower fuel bills. This efficiency advantage, coupled with its dynamic prowess and elegant interior, makes the M340i a preferred choice for those requiring a powerful daily driver that’s also practical for longer commutes. To learn more about all BMW fuel economy data, our extensive database is a good resource.

Tips to maximize efficiency

Employing the vehicle’s “Eco Pro” driving mode is the most straightforward way to nudge the M340i’s efficiency upwards. This mode subtly adjusts throttle response, transmission shift points, and even climate control settings to prioritize fuel savings without drastically hindering momentum, making it ideal for cruising.

Maintain consistent tire pressure at the manufacturer’s recommended levels. Under-inflated tires increase rolling resistance, forcing the engine to work harder and consuming more fuel, especially at higher speeds where the effect is compounded.

Capitalize on the mild-hybrid system by driving smoothly. Anticipate stops, coast when safe and appropriate, and accelerate gradually. The M340i is designed for this kind of efficient, deliberate driving just as much as it is for aggressive bursts of speed.

Minimize unnecessary weight. While not always practical, removing heavy items from the trunk or back seat that aren’t regularly needed can incrementally improve fuel economy, particularly in stop-and-go city driving where acceleration demands are frequent.

Plan your routes to avoid excessive idling and heavy traffic whenever possible. The M340i’s mild-hybrid system manages start/stop beautifully, but eliminating unnecessary stops and starts altogether is always the most efficient approach.