25 MPG combined won’t break any fuel efficiency records, but for the 2015 BMW 428i xDrive Convertible, it’s a reasonable compromise. This car isn’t about maximizing efficiency. It’s made for enjoying top-down driving with some performance and all-weather capability. Buyers usually care more about style, the BMW badge, and a fun driving experience than getting every last mile from a gallon of premium fuel.

City and highway performance

The EPA estimates are 21 MPG in the city and 32 MPG on the highway. The city number reflects stop-and-go traffic and the weight of the xDrive all-wheel-drive system. The 32 MPG highway rating shows the 428i Convertible can cover long distances efficiently. The eight-speed automatic transmission helps by keeping the engine at the right RPM for power and fuel savings. Remember that these numbers are from controlled tests. Driving hard or using Sport mode often will lower the highway MPG.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2015 BMW 428i xDrive Convertible at $2,300. This assumes 15,000 miles per year and national average premium gasoline prices, which the 428i requires. Your actual fuel costs will change based on how you drive, city versus highway driving, and local fuel prices. Someone who mostly drives short distances in heavy traffic will likely spend more than $2,300, while someone who mainly takes long road trips might spend a bit less.

Real-world expectations

The EPA provides a standard, but real-world fuel economy often differs. Many things affect actual MPG. Driving style, tire pressure, outside temperature, and even the gasoline grade can change efficiency. Owners of the 2015 428i xDrive Convertible often report numbers close to the EPA estimates, but fast driving, especially with the top down, will decrease fuel economy. If you frequently use the car’s power and listen to the exhaust, expect your average MPG to drop toward 20 MPG.

How it compares

Compared to its competitors, the 2015 BMW 428i xDrive Convertible’s fuel economy is generally competitive, but not the best. A Mercedes-Benz C300 Convertible from the same year, with its 2.0L turbo engine, gets similar numbers, about 22 MPG city and 31 MPG highway in RWD form. The 4MATIC all-wheel-drive systems typically reduce these slightly. An Audi A5 Cabriolet, also with a 2.0L turbo and Quattro all-wheel-drive, has comparable numbers, hovering around 24MPG combined. The Infiniti Q60 Convertible, with its larger V6 engine, is much lower, struggling to reach 20 MPG combined. These comparisons matter to buyers because they show the 428i balances performance and fuel use well within its class. Explore all Bmw fuel economy data for a wider view, and also review 428I MPG across all years for trends and variances.

Tips to maximize efficiency

The 2015 428i xDrive Convertible isn’t a hybrid, but it still benefits from good driving habits. Avoid accelerating quickly and braking hard when you can. Smooth, gradual movements will help the engine work more efficiently and reduce fuel consumption. Use Eco Pro mode when cruising at constant speeds on the highway. This mode changes the throttle and transmission to focus on fuel economy over performance.

Regular maintenance is important for the best fuel efficiency. Keep your tires inflated to the recommended pressure, since low tires increase rolling resistance and lower MPG. Also, follow the oil change and air filter replacement schedules to keep the engine running smoothly.

Reduce extra weight in the car. Take out anything from the trunk or back seats that you don’t need every day. Extra weight makes the engine work harder, which reduces fuel economy. The 428i xDrive’s added weight from the AWD system already impacts fuel economy, so reducing unnecessary weight can help to offset this impact.

Plan your routes to avoid traffic if possible. Stop-and-go traffic uses much more fuel than steady driving. Use navigation apps to find different routes that might have less traffic, even if they are a little longer. Consider using cruise control on the highway to keep a steady speed and improve fuel efficiency.