22 MPG combined won’t make the 2017 BMW 640i xDrive Convertible a winner when it comes to fuel economy. It’s also unlikely to deter buyers who prioritize open-air thrills, effortless power, and exclusivity. This isn’t a car bought for its fuel sipping; it’s purchased for the experience, and those who buy it understand the trade-offs.

City and highway performance

The EPA estimates that the 2017 BMW 640i xDrive Convertible, equipped with its turbocharged 3.0L inline-six engine and eight-speed automatic transmission, will achieve 19 MPG in the city and 28 MPG on the highway. These figures are because of the 315-horsepower engine that hauls around all-wheel drive and a heavy convertible structure. Stop-and-go traffic will always be the enemy, while steady-state cruising allows the engine to stretch its legs and approach that highway number.

Annual fuel cost

The EPA calculates the annual fuel cost for the 2017 BMW 640i xDrive Convertible to be $2,650. This figure is based on driving 15,000 miles per year, with a percentage of those miles split between city and highway driving, and using national average fuel prices at the time of calculation. This is a useful benchmark for comparing against other vehicles, but your actual fuel expenses will depend on your driving habits, local fuel costs, and how often you accelerate.

Real-world expectations

While the EPA provides a standardized testing methodology, real-world fuel economy often varies. The 640i xDrive Convertible encourages drivers to enjoy its performance, and frequent use of the accelerator pedal will lead to lower MPG than the official figures suggest. However, those who primarily use the car for relaxed highway cruising, watching the speedometer, may find they can meet or slightly exceed the 28 MPG estimation. The 640I MPG across all years shows similar trends, highlighting the consistent trade-off between performance and efficiency across the model line. The turbocharged engine is responsive, making quick bursts of speed readily available, but that will affect your fuel bill.

How it compares

Compared to its contemporaries, the 2017 BMW 640i xDrive Convertible’s fuel economy is as expected. A similarly equipped Audi S5 Cabriolet, with its supercharged V6, achieves figures around 21 MPG combined, putting it close to the BMW. A Mercedes-Benz E400 Cabriolet (pre-2018 revision), packing a turbocharged V6, delivered slightly better numbers in most tests, hovering around 23 MPG combined. These differences are subtle, and purchase decisions for this type of vehicle rarely depend solely on a single MPG point or two. Buyers considering all Bmw fuel economy data will recognize that performance and luxury often come at a cost. Even within the BMW family, a lower-end 4 Series convertible will offer better fuel economy, but at the expense of power and prestige.

Tips to maximize efficiency

Take advantage of the BMW’s driving mode selector. Switching to “Eco Pro” mode will remap the throttle response, adjust the transmission shift points, and reduce the energy consumption of ancillary systems. While it might slightly diminish the driving experience, it can make a noticeable difference on longer journeys.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, forcing the engine to work harder and consuming more fuel. Refer to the sticker on the driver’s side doorjamb for the recommended tire pressure and check it regularly, especially during temperature fluctuations.

Avoid unnecessary idling. Modern engines do not require long warm-up periods. Idling burns fuel without covering any distance. If you anticipate stopping for more than a minute, it’s generally more fuel-efficient to turn off the engine and restart it when you’re ready to go.

Anticipate traffic flow and maintain a consistent speed whenever possible. Frequent acceleration and braking consume significantly more fuel than smooth, gradual changes in speed. Look ahead, anticipate traffic signals, and avoid unnecessary bursts of acceleration.

Use cruise control on the highway. Cruise control helps maintain a constant speed, reducing unnecessary acceleration and deceleration. This can significantly improve highway fuel economy, especially on long drives where subtle speed variations can add up over time.