25 MPG combined isn’t going to win any hypermiling contests, but in the 2015 BMW M235i Convertible, it’s almost beside the point. This isn’t a car bought for its eco-credentials; it’s a reward, a weekend escape machine powered by a charismatic inline-six. The fuel economy is simply the price of admission to a world of sharp handling, brisk acceleration, and open-air thrills. It’s a trade most M235i Convertible owners happily make.

City and highway performance

The EPA estimates for the 2015 M235i Convertible put city driving at 21 MPG and highway cruising at 31 MPG. The city number will change depending on how you drive the car. Frequent sprints away from stoplights will drop that figure quickly, while gentler inputs will yield better results. The highway number is more consistent, aided by the smooth eight-speed automatic transmission. This gearbox helps keep the engine in its sweet spot for both responsiveness and efficiency when you’re simply covering ground. While the automatic is the sole transmission choice for the convertible, it is well-suited to the car’s character, offering quick shifts in Sport mode and relaxed cruising in Comfort.

Annual fuel cost

The EPA calculates the annual fuel cost for the 2015 BMW M235i Convertible at $2,300, based on driving 15,000 miles per year and using national average fuel prices. This is a standardized figure designed for comparison purposes. Your actual fuel costs will vary depending on how many miles you drive and the prevailing fuel prices in your area. Drivers who frequently tap into the M235i’s performance potential should also budget for premium fuel, which is recommended to maintain optimal performance and prevent engine knocking.

Real-world expectations

Few M235i Convertible owners are concerned with matching the EPA’s numbers exactly. They prioritize the driving experience and are willing to accept slightly lower fuel economy in exchange. If you drive with a light foot, expect to see numbers hovering around the EPA estimates. However, if you spend a lot of time in Sport mode or enjoy backroad blasts, the real-world MPG will likely land a few notches below the official figures. Take a look at M235I MPG across all years to see what other drivers are reporting. The payoff, though, is a level of driving engagement that few other cars in this class can match.

How it compares

Compared to its peers, the 2015 M235i Convertible’s fuel economy is about average for a performance-oriented convertible. A 2015 Porsche Boxster S, for example, offers a similar blend of performance and open-air driving, achieving an EPA-rated 22 MPG combined with its PDK transmission. The Audi TT Roadster, in its turbocharged 2.0-liter form, manages a slightly better 26 MPG combined. However, the Audi lacks the BMW’s straight-six soundtrack and overall driving feel. The M235i strikes a chord with drivers who value performance over outright fuel efficiency, accepting a small compromise at the pump for a big gain in driving satisfaction. For all Bmw fuel economy data, see our brand hub.

Tips to maximize efficiency

While the M235i Convertible isn’t designed for ultimate fuel economy, there are still ways to improve its efficiency. Use the Eco Pro mode, which remaps the throttle response and shift points to prioritize fuel savings. This mode is best suited for highway cruising or stop-and-go traffic where aggressive acceleration isn’t necessary.

Avoid unnecessary idling. The turbocharged engine consumes fuel even when stationary. If you are stopped for more than a minute or two, switch off the ignition to save fuel. This is especially important in urban environments where idling is common.

Keep your tires properly inflated. Underinflated tires increase rolling resistance, which reduces fuel economy. Check your tire pressure regularly and inflate them to the recommended level, found on a sticker inside the driver’s side doorjamb.

Reduce your vehicle’s weight. Carrying unnecessary cargo increases fuel consumption. Remove any items you don’t need from the trunk and passenger compartment. A lighter car requires less energy to accelerate and maintain speed.

Drive smoothly and avoid aggressive acceleration. The M235i’s turbocharged engine is responsive, but rapid acceleration burns fuel. Anticipate traffic flow and use a gentle touch on the accelerator to maximize fuel efficiency.