23 MPG combined is the price of admission to open-air motoring with a silken inline-six and a BMW badge. No one buys a 2017 BMW 640i Convertible expecting Prius-like frugality; they buy it for the effortless power, the image, and the wind-in-your-hair experience. This is a vehicle purchased with the heart, not the calculator, but understanding its fuel consumption within the context of its mission is still worthwhile.

City and highway performance

The EPA estimates 20 MPG in the city and 29 MPG on the highway for the 2017 BMW 640i Convertible, figures achieved thanks to the 315 horsepower turbocharged 3.0L inline-six and the smooth-shifting eight-speed automatic transmission. The highway number, in particular, is respectable for a car of this size and performance capability, owing to the transmission’s tall gearing and the engine’s willingness to cruise comfortably at low RPMs. City driving, with its stop-and-go nature and reliance on boost, is where the 640i’s fuel consumption is most noticeable. However, the car’s relatively light weight (compared to some competitors) helps mitigate the impact of frequent acceleration.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2017 BMW 640i Convertible at $2,500. This figure is based on driving 15,000 miles per year and using national average fuel prices. Individual costs will vary depending on driving habits, location, and fuel prices at the pump. Considering the 640i’s premium positioning and the likelihood that owners will opt for premium fuel, exceeding this annual cost is entirely possible. Prudent drivers who prioritize highway miles and avoid aggressive acceleration may find themselves slightly below this estimate, but $2,500 is a realistic benchmark for most owners.

Real-world expectations

While the EPA provides a standardized estimate, real-world fuel economy can fluctuate significantly. Aggressive driving, frequent short trips, and consistent city driving will inevitably lower fuel economy below the EPA estimates. Conversely, long highway trips at consistent speeds, judicious use of the throttle, and careful maintenance (including proper tire inflation) can help drivers achieve results closer to the EPA’s highway figure.

Based on owner reports and anecdotal evidence, expect a real-world combined MPG figure in the low 20s, possibly dipping into the high teens with a heavy foot.

How it compares

The 2017 BMW 640i Convertible’s fuel economy places it in the middle of its competitive set. The Mercedes-Benz SL450, with its 3.0L V6, achieves similar numbers, around 20 MPG city and 28 MPG highway. The Jaguar F-Type Convertible, especially the V6 models, generally delivers slightly lower fuel economy, typically in the high teens combined. Even the Porsche 911 Carrera Cabriolet, known for its efficient powertrains, doesn’t stray too far from the 640i’s figures, achieving around 22 MPG combined. The differences are negligible to the target buyer, whose focus is on performance and luxury rather than maximizing fuel savings. If one is looking at all Bmw fuel economy data, the 640i resides near the low end, but the body style plays a large role in this. Anyone already doing research on 640I MPG across all years will realize this.

Tips to maximize efficiency

Take advantage of the 640i’s driving modes. Selecting “Eco Pro” mode will remap the throttle response, adjust the shift points of the eight-speed automatic, and even modify the climate control settings to improve fuel efficiency. This is a subtle adjustment in the car’s character and can easily benefit one’s average fuel economy.

Minimize idling. The turbocharged engine consumes fuel even when stationary. Avoid excessive idling, especially in situations like waiting in parking lots or drive-throughs. Turn off the engine if you anticipate a prolonged stop, saving fuel and reducing emissions.

Maintain proper tire inflation. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressures regularly and inflate them to the recommended levels (found on the driver’s side doorjamb) to optimize efficiency and handling.

Practice smooth acceleration and braking. Avoid sudden bursts of acceleration and hard braking, as these actions consume more fuel. Anticipate traffic flow and maintain a consistent speed to minimize energy waste. The 640i’s ample torque allows for effortless cruising, so avoid unnecessary downshifts.

Consider a less spirited driving style. While the 640i Convertible is undeniably fun to drive, resisting the urge to constantly exploit its performance potential will yield tangible benefits at the fuel pump. Embrace the car’s luxurious character and enjoy relaxed open-air cruising, rather than treating every drive as a race.