23 MPG combined isn’t going to win any awards for saving gas, but it’s perfectly acceptable for a luxurious, all-wheel-drive convertible that prioritizes open-air thrills and effortless performance. The 2021 BMW 840i xDrive Convertible isn’t bought by those hyper-focused on maximizing fuel efficiency; its buyers are typically successful professionals or empty-nesters seeking a stylish and engaging grand tourer. They prioritize exhilaration and comfort over outright thriftiness, and the 840i delivers both. The slight compromise at the pump becomes a secondary consideration compared to the sensory experience this car provides.

City and highway performance

The EPA estimates for the 2021 BMW 840i xDrive Convertible put city driving at 20 MPG and highway cruising at 27 MPG. The city figure reflects the stop-and-go nature of urban environments, where the 3.0L turbocharged inline-six engine inevitably spends more time idling and accelerating from a standstill. The highway number is more promising and achievable during steady-state cruising, thanks to the smooth-shifting 8-speed automatic transmission (S8) which keeps the engine in its most efficient range at higher speeds. Drivers with longer suburban commutes will likely see results closer to the combined rating, balancing both types of driving.

Annual fuel cost

According to the EPA, the estimated annual fuel cost for the 2021 BMW 840i xDrive Convertible is $2,500. This is based on 15,000 miles of driving per year, with a mix of city and highway conditions, and using the national average fuel price at the time of calculation. Individual costs will vary depending on driving habits, local fuel prices, and the actual number of miles driven annually.

Someone who primarily uses their 840i for weekend jaunts will spend less, while those who use it for daily commuting will likely exceed the $2,500 mark.

Real-world expectations

While the EPA estimates provide a useful benchmark, real-world MPG can often vary. Drivers who frequently engage the 840i’s Sport mode and exploit its impressive acceleration will undoubtedly see lower fuel economy figures than those who prioritize smooth and consistent driving. Conversely, patient drivers who use the Eco Pro mode and anticipate traffic flow can potentially nudge the MPG closer to, or even slightly above, the EPA estimates.

Several factors like tire inflation, ambient temperature, and even the choice of fuel grade can also contribute to MPG fluctuations.

How it compares

The fuel economy of the 2021 BMW 840i xDrive Convertible places it squarely in line with other similarly configured luxury convertibles. For example, the Mercedes-Benz SL 450, another comparable luxury convertible, offers only slightly better EPA estimates, hovering around 21 MPG combined. Other competitors, like the Porsche 911 Carrera Cabriolet, can achieve similar or slightly better numbers depending on configuration and driving style, but they command a higher price tag. For those looking for improvements in the BMW range, they could consider researching 840I MPG across all years. The 840i’s balance of performance, luxury, and acceptable fuel economy makes it a strong option within its competitive set. For those considering the wider offering from BMW, you can see all Bmw fuel economy data.

Tips to maximize efficiency

Optimize tire pressure according to the manufacturer’s specifications, which can be found on the doorjamb sticker or in the owner’s manual. Underinflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel. Regularly checking and maintaining proper tire pressure is a simple yet effective way to improve fuel efficiency.

Use the 840i’s Eco Pro driving mode when appropriate. This mode adjusts the throttle response, transmission shift points, and climate control settings to prioritize fuel conservation. While it might slightly diminish the car’s sporty responsiveness, Eco Pro is ideal for highway cruising and less engaging driving scenarios.

Avoid aggressive acceleration and hard braking. The 840i xDrive Convertible’s turbocharged engine responds well to a smooth and progressive driving style. Anticipate traffic flow and maintain a consistent speed whenever possible. Minimize rapid acceleration and deceleration to reduce fuel consumption.

Reduce unnecessary weight in the vehicle. Carrying excessive cargo adds strain to the engine and impacts fuel efficiency. Remove any items that are not essential, especially heavy objects in the trunk. A lighter vehicle requires less energy to propel, resulting in improved MPG.

Minimize idling time. Idling consumes fuel without covering any distance. If you anticipate a prolonged stop, such as waiting at a train crossing or a construction zone, consider turning off the engine. Restarting the engine consumes less fuel than idling for extended periods.