24 MPG combined won’t win any hypermiling competitions, but it’s acceptable in the 2025 BMW 840i xDrive Convertible. This isn’t a car for ultimate fuel efficiency; it’s a statement, a visceral experience, a luxurious indulgence. Affluent professionals and empty-nesters who want open-air thrills and effortless performance understand this trade-off. They want a car that turns heads and delivers a refined driving experience, and they’re willing to pay for it at the dealership and at the pump.

City and highway performance

The EPA estimates the 840i xDrive Convertible’s fuel economy at 21 MPG in the city and 29 MPG on the highway. The city figure reflects urban stop-and-go driving, where the engine idles or accelerates from a standstill more often. The highway number reveals the car’s potential. Its smooth 8-speed automatic transmission (S8) and the inherent efficiency of its 3.0L inline-six engine at cruising speeds make achieving close to 30 MPG on long road trips realistic, but these figures are based on standardized testing, and aggressive driving habits will always impact real-world results. You can research 840I MPG across all years to see how the current model compares to its predecessors.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2025 BMW 840i xDrive Convertible at $2,400. This is calculated based on driving 15,000 miles per year, using the national average fuel price. This is simply an estimate, as individual spending varies based on driving habits, local fuel prices, and the type of fuel used. While the 840i doesn’t require premium fuel, it is recommended for optimal performance. Using regular gasoline can reduce horsepower and fuel economy, negating any potential savings at the pump.

Real-world expectations

The EPA provides a benchmark, but real-world fuel economy often differs. Drivers who accelerate quickly and take frequent short trips around town will likely see figures closer to the city MPG estimate, maybe even slightly lower. Those who drive smoothly and consistently on the open road should match or exceed the EPA’s highway rating. Tire pressure, vehicle maintenance, and weather conditions can subtly influence fuel consumption. Ultimately, your mileage hinges on how and where you drive.

How it compares

The 840i xDrive Convertible’s fuel economy is in the middle of the luxury convertible pack. The Mercedes-Benz SL 450, is rated at 21 MPG combined, slightly lower than the BMW. The Porsche 911 Carrera Cabriolet achieves around 20 MPG combined in some configurations, with its rear-engine layout and focus on performance. An Audi S5 Cabriolet is closer, achieving 24 MPG combined as well, but offers less power. For buyers considering a performance-oriented convertible, the 840i offers a balance of power, luxury, and reasonable fuel consumption. This comparison matters because buyers may be looking at multiple options that all offer the same driving experience. Be sure to look at all Bmw fuel economy data, too.

Tips to maximize efficiency

Avoid aggressive acceleration. The 840i xDrive Convertible’s twin-turbo inline-six delivers power on demand, but each burst of acceleration comes at a cost. Smooth, gradual acceleration enhances the driving experience and minimizes fuel consumption.

Maintain proper tire inflation. Underinflated tires increase rolling resistance, forcing the engine to work harder and burn more fuel. Consult the sticker on the driver’s side doorjamb for the recommended tire pressure, and check your tires regularly, especially before long trips.

Minimize idling. Letting the engine idle for extended periods, such as waiting in a parking lot, wastes fuel and causes unnecessary wear and tear. If you anticipate a prolonged stop, turn off the engine.

Use cruise control on the highway. Maintaining a consistent speed on the highway with cruise control helps to optimize fuel efficiency. Avoid sudden speed changes.

Keep up with scheduled maintenance. Regular oil changes, air filter replacements, and spark plug maintenance ensure your engine runs efficiently. Follow the manufacturer’s recommended maintenance schedule to keep your 840i xDrive Convertible performing well.