19 MPG combined is the reality for anyone considering the 2021 BMW M850i xDrive Convertible with its strong 4.4L V8. Let’s be clear: nobody buys this car for its fuel efficiency. They buy it for the blend of performance, luxury, and open-air thrills that few cars can match. The M850i Convertible is a statement, a reward, a visceral experience, and fuel economy isn’t what buyers think about first. They’re focused on the 523 horsepower, the impeccable interior, and the envious glances they receive gliding down the boulevard. This is a car for those who prioritize experiences over economy.

City and highway performance

The M850i’s EPA ratings break down to 17 MPG in the city and 24 MPG on the highway. The low city MPG reflects the engine’s power and the temptation to tap into it frequently. Stop-and-go traffic inevitably takes a toll. The highway figure of 24 MPG is more respectable, demonstrating that the engine can achieve reasonable efficiency when cruising at steady speeds, although resisting the urge to unleash the twin-turbo V8 for passing maneuvers is key. These numbers shouldn’t be a surprise, given the M850i’s performance capabilities; physics dictates that power requires fuel.

Annual fuel cost

According to the EPA, the annual fuel cost for the 2021 BMW M850i xDrive Convertible is approximately $3,050. This figure is based on driving 15,000 miles per year and using the national average fuel price at the time of calculation. Of course, your actual fuel costs may vary depending on your driving habits, the type of fuel you use (premium is recommended), and local fuel prices. However, the $3,050 figure provides a reasonable benchmark for budgeting purposes. Those who frequently drive fast will likely exceed this amount.

Real-world expectations

While the EPA provides an estimate, real-world MPG can vary considerably. Drivers who spend most of their time in heavy city traffic, or frequently use the engine’s performance, can expect to see figures lower than the official ratings. Drivers who primarily cruise on highways and drive more conservatively might achieve slightly better mileage. Remember that factors like tire pressure, vehicle maintenance, and even weather conditions can influence fuel economy. The M850i is a complex machine, and its fuel consumption is sensitive to variables.

How it compares

When considering the M850i’s competition, the fuel economy picture becomes clearer. A comparable Mercedes-AMG SL63 achieves roughly the same combined MPG, with the models in the current generation delivering estimates of 16 MPG city, 24 MPG highway. The Porsche 911 Cabriolet, while offering a somewhat different driving experience, can achieve slightly better fuel economy, especially in base Carrera form; the current generation Carrera models achieve around 27 MPG highway. But, opting for the higher performance 911 variants, such as the Carrera S or Turbo, will see those numbers drastically decrease. The M850i’s fuel economy is competitive within its class of high-performance convertibles. If fuel efficiency is a primary concern, buyers might consider alternatives like the BMW 4 Series Convertible (offering much better MPG) but sacrifice the M850i’s power and prestige. See all Bmw fuel economy data if you want to explore all options from BMW.

Tips to maximize efficiency

While the M850i isn’t fuel-efficient, there are steps you can take to optimize its MPG. Avoid aggressive acceleration and braking; the smoother your driving style, the less fuel you’ll consume. This V8 rewards careful drivers.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressures regularly and inflate them to the recommended levels, which are listed on a sticker inside the driver’s side door jamb.

Use the M850i’s driving modes strategically. The “Eco Pro” mode, if equipped, prioritizes fuel efficiency by optimizing engine settings and throttle response. While it might not be ideal for fast driving, it can noticeably improve MPG during everyday commuting. Explore M850I MPG across all years.

Minimize idling. If you’re stopped for more than a minute or two, turn off the engine. Excessive idling consumes fuel unnecessarily, especially in a large-displacement engine like the M850i’s V8. Modern cars are designed to restart quickly, so switch off the engine when it’s safe to do so.

Keep your vehicle properly maintained. Regular oil changes, air filter replacements, and spark plug replacements can help ensure that your engine is running efficiently. Consult your owner’s manual for the recommended maintenance schedule.