25 MPG combined isn’t going to win any hypermiling contests, but it’s a figure most 2021 BMW M340i xDrive owners can happily live with. This isn’t a car purchased for maximizing efficiency; it’s a performance sedan with teeth, and that respectable mileage comes alongside a healthy dose of power and all-weather confidence. The M340i xDrive delivers a blend of athleticism and practicality, attracting buyers who want driving thrills without completely abandoning reason at the pump.

City and highway performance

The EPA’s breakdown reveals 22 MPG in the city and 31 MPG on the highway. The city number reflects the reality of stop-and-go driving, where the M340i’s turbocharged engine spends more time idling or accelerating moderately. The highway figure, on the other hand, showcases the engine’s efficiency at sustained speeds, where the 8-speed automatic transmission (S8) can settle into its higher gears and the engine loafs along. These numbers make sense for a car capable of sub-5-second 0-60 mph sprints, and the highway MPG especially lends itself to comfortable and relatively economical long-distance cruising.

Annual fuel cost

According to the EPA, the annual fuel cost for the 2021 BMW M340i xDrive is $2,300. This calculation is based on driving 15,000 miles per year and using national average fuel prices. Naturally, the actual amount spent on fuel will vary depending on individual driving habits, fuel prices in your area, and the percentage of city vs. highway driving. But the $2,300 figure provides a useful benchmark for comparison and budgeting.

Real-world expectations

While the EPA numbers are a good starting point, real-world fuel economy can often differ. Aggressive driving, frequent short trips, and extreme weather conditions can all lower your MPG. Conversely, careful driving habits, primarily highway miles, and diligent maintenance can push fuel economy closer to, or even slightly above, the EPA estimates. Owners who prioritize fuel efficiency can likely achieve figures near the EPA estimates, while those who frequently exploit the M340i’s performance potential should expect lower numbers. To see the M340I MPG across all years, check our detailed data page.

How it compares

The M340i sits in a competitive segment where performance and fuel economy are often traded off. The Audi S4, with its 349-horsepower turbocharged V6 and standard all-wheel drive, achieves a combined EPA rating of 24 MPG. The Mercedes-AMG C43 Sedan, another strong contender, delivers similar performance, but only manages 22 MPG combined. Even the Genesis G70 3.3T, known for its value and potent twin-turbo V6, achieves only 20 MPG combined. These subtle differences matter to buyers weighing the pros and cons before deciding which luxury performance model best suits their needs. Review all Bmw fuel economy data to get a wider perspective.

Tips to maximize efficiency

Take advantage of the M340i’s Eco Pro mode. This driving mode adjusts throttle response, transmission mapping, and climate control settings to prioritize fuel efficiency. While it might temper the engine’s responsiveness, it can make a noticeable difference on longer trips or in heavy traffic. Experiment with it to discover the right balance between fuel savings and driving enjoyment for your particular needs.

Pay attention to tire pressure. Underinflated tires increase rolling resistance and reduce fuel economy. Regularly check your tire pressure and inflate them to the recommended level, which can be found on the sticker inside the driver’s side doorjamb. This simple maintenance task can improve MPG by a few percent.

Avoid excessive idling. Modern engines are remarkably efficient, and idling consumes fuel without covering any distance. If you’re stopped for more than a minute or two, especially in traffic, consider turning off the engine. Many modern cars, including the M340i, have an auto stop/start feature that does this automatically, though it can be disabled if you find it intrusive.

Drive smoothly and anticipate traffic flow. Avoid aggressive acceleration and braking, as these actions waste fuel. Instead, adopt a smooth driving style and maintain a consistent speed whenever possible. By anticipating traffic and coasting to decelerate, you can minimize the need for hard braking and improve fuel economy.