25 MPG combined isn’t going to win any hypermiling contests, but in the realm of luxurious, open-top grand tourers, the 2021 BMW 840i Convertible holds its own. This isn’t a car bought for maximizing every last drop of fuel; it’s a statement, a reward, and a machine engineered for effortless cross-country cruises. The typical buyer prioritizes a refined driving experience, a powerful engine note, and wind-in-your-hair exhilaration over pinching pennies at the pump. They accept the fuel consumption as the cost of admission to an exclusive club.

City and highway performance

The 840i Convertible’s EPA ratings break down to 22 MPG in the city and 29 MPG on the highway. The city figure reflects the stop-and-go nature of urban driving, where the turbocharger is constantly spooled up and the engine works harder. Overcoming inertia contributes to this. The highway number is more impressive, showcasing the efficiency of the smooth-shifting eight-speed automatic transmission in its higher gears. At steady state cruising speeds, the engine loafs along, delivering respectable fuel economy while still providing ample reserve power for passing. These numbers reflect a balance: performance when you want it and reasonably efficient cruising when you don’t.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 BMW 840i Convertible at $2,300. This figure is based on driving 15,000 miles per year and a calculated percentage of city versus highway miles, using national average fuel prices. Premium fuel is required, naturally. Individual spending will depend on driving habits and local fuel costs, but this provides a reliable benchmark for budgeting. For owners spending this kind of money on a car, it likely is not a deciding factor.

Real-world expectations

While the EPA estimates provide a useful reference point, real-world fuel economy can vary based on several factors. Aggressive driving, particularly frequent hard acceleration, will significantly reduce MPG. Sticking to a conservative driving style, avoiding unnecessary idling, and maximizing highway cruising can potentially improve upon the EPA figures.

The 840i’s driving mode selector can also influence fuel consumption. Eco Pro mode prioritizes efficiency by adjusting throttle response and transmission mapping, while Sport and Sport+ modes unleash the engine’s full potential at a greater cost to economy. Keep in mind that all Bmw fuel economy data will be based on the EPA’s tests, and your figures may vary.

How it compares

Compared to its competitors, the BMW 840i Convertible fares reasonably well in terms of fuel economy. The Mercedes-Benz SL 450, with its similar 3.0L turbo six, posts similar MPG figures, hovering around 20 MPG city and 28 MPG highway. The Porsche 911 Carrera Cabriolet delivers slightly better fuel economy, with some configurations achieving around 21 MPG city and 30 MPG highway, but at a generally higher price point. The 840I MPG across all years shows fuel trends for this vehicle.

The Lexus LC 500 Convertible, with its naturally aspirated 5.0L V8, stands out as the thirstiest of the bunch, with EPA estimates typically in the high teens for city driving and mid-20s for highway.

Tips to maximize efficiency

Embrace gentle acceleration. The 840i’s turbocharged engine provides plenty of torque, so avoid flooring the throttle unless necessary. A smooth application of power will conserve fuel and maintain a quiet driving experience.

Use the Eco Pro driving mode when cruising on the highway or navigating congested city streets. This mode optimizes the engine and transmission settings for maximum efficiency by reducing throttle response and encouraging earlier upshifts.

Ensure that your tires are properly inflated to the recommended pressure. Underinflated tires increase rolling resistance, which negatively impacts fuel economy. Check your tire pressures regularly, especially during seasonal temperature changes.

Minimize idling time whenever possible. Modern engines consume fuel even when stationary, so avoid prolonged idling at traffic lights or when waiting for someone. Shutting off the engine is often more efficient than letting it run unnecessarily.

Plan your routes strategically to avoid traffic congestion and unnecessary stop-and-go driving. Using navigation systems to identify and bypass heavily congested areas can save fuel and reduce stress.