24 MPG combined is likely not a primary concern for buyers of the 2020 BMW 840i Convertible. It’s a car purchased for its performance, luxury, and open-air experience, rather than frugality. The 840i Convertible prioritizes wind and sun over maximizing miles per gallon, and its drivers are comfortable with premium fuel and spirited driving.

City and highway performance

The EPA estimates 22 MPG in the city for the 840i Convertible and 29 MPG on the highway. City driving, with its stop-and-go nature, rarely benefits performance vehicles. Expect even lower numbers if you frequently use the 3.0L turbocharged inline-six’s power in the city. Highway cruising provides a more consistent and efficient experience. The 8-speed automatic transmission selects a relaxed gear, allowing the engine to conserve fuel while maintaining comfortable cruising speeds. Achieving the EPA’s 29 MPG figure on the open road is possible if you avoid constant overtaking. If you’re curious about 840I MPG across all years, there are resources available for older models as well.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,400 for the 2020 BMW 840i Convertible. This is based on driving 15,000 miles per year, with a mix of city and highway driving, and using national average fuel prices for premium gasoline, which is required. While $2,400 might seem significant, it’s a relatively small price for owners already committed to the car’s luxury and performance and is unlikely to change their buying decision.

Real-world expectations

Real-world fuel economy for the 840i Convertible will vary depending on driving style, traffic, and road types. Aggressive acceleration, frequent short trips, and exceeding speed limits will decrease fuel efficiency. A more relaxed driving style, longer trips at consistent speeds, and anticipation of traffic can help you approach or exceed the EPA estimates. Expect figures closer to 20-22 MPG in typical mixed driving conditions. Owners who prioritize performance over fuel savings should expect even lower MPG.

How it compares

The 840i Convertible’s fuel economy is typical compared to other luxury convertibles. The Mercedes-Benz SL 450, with its 3.0L V6, achieves around 20 MPG combined. The Porsche 911 Carrera Cabriolet, manages around 20 MPG combined with the base engine. The Jaguar F-Type Convertible posts similar figures of around 23 MPG combined with its supercharged V6. The Aston Martin Vantage Roadster sees figures closer to 18MPG combined. These comparisons show that the 840i Convertible isn’t an outlier. Buyers in this market prioritize driving experience and prestige over fuel savings. You can find all Bmw fuel economy data on this site, covering a wide range of models.

Tips to Maximize Efficiency

Use the 840i’s Eco Pro mode which optimizes engine and transmission settings. While it might slightly dull the throttle response, it can make a noticeable difference on longer drives, especially on the highway.

Ensure your tires are properly inflated. Under-inflated tires increase rolling resistance, forcing the engine to work harder. Check your tire pressures regularly and inflate them to the manufacturer’s recommended settings, found on the doorjamb.

Avoid unnecessary idling. If you’re stopped for more than a minute, turn off the engine. Modern engines restart quickly, and idling wastes fuel. The 840i’s automatic start/stop system can help with this in the city.

Practice smooth acceleration and braking. Avoid sudden bursts of speed and hard braking. Anticipate traffic and maintain a consistent speed when possible. The smoother you drive, the less fuel you’ll consume.

Schedule regular maintenance. A well-maintained engine runs more efficiently. Follow the manufacturer’s recommended maintenance schedule, including oil changes, filter replacements, and tune-ups. Addressing issues early can prevent them from impacting fuel economy.