The 2017 Mercedes-Benz E400 Convertible gets 23 MPG combined. This isn’t a number that’s going to impress the Prius crowd, nor is it meant to. This car is about experiencing the sunshine, hearing the subtle growl of the turbocharged six-cylinder engine, and arriving in style. The E400 Convertible isn’t bought by penny-pinchers; it’s acquired by those who value luxury, performance, and the distinct pleasure of top-down driving above ultimate fuel efficiency.

City and highway performance

The EPA estimates the E400 Convertible will achieve 20 MPG in the city and 29 MPG on the highway. This split reveals the E400’s personality. Around town, the turbo six provides ample power, making short work of stop-and-go traffic. However, all that effortless acceleration impacts fuel consumption. Out on the open road, the story changes. The 7-speed automatic transmission allows the engine to relax at higher speeds, resulting in more pleasing highway fuel economy. These numbers suggest that extended highway drives will prove far more efficient than urban errands, aligning with the E400 Convertible’s grand-touring aspirations.

Annual fuel cost

According to the EPA, the annual fuel cost for the 2017 Mercedes-Benz E400 Convertible is $2,500. This figure is based on driving 15,000 miles per year, using a national average fuel price. Individual spending may vary depending on your driving habits and fluctuations in fuel prices. If you drive significantly more than 15,000 miles annually or live in an area with particularly high fuel costs, you can expect to exceed this estimate. Those who drive less may spend less. The $2,500 figure is a baseline, not an absolute.

Real-world expectations

While the EPA estimates provide a useful baseline, real-world MPG often deviates. Factors such as driving style, traffic conditions, and even tire pressure can significantly impact fuel economy. Aggressively accelerating from a stop or consistently exceeding the speed limit will noticeably reduce MPG. Hills and headwinds will also place greater demands on the engine. Expect to see a variance of +/- 2-3 MPG from the EPA estimates depending on driving conditions. Understanding that these factors can shift E400 MPG across all years helps buyers get the most realistic expectations.

How it compares

In the realm of luxury convertibles, the E400’s fuel economy lands somewhere in the middle of the pack. A 2017 BMW 440i Convertible, with its turbocharged inline-six, achieves a similar 25 MPG combined. However, a V8-powered alternative like the Lexus RC F Convertible dips significantly lower, struggling to achieve even 19 MPG combined. On the more efficient end, a four-cylinder model such as the Audi A5 Convertible may be able to stretch a gallon of fuel further, approaching 27 MPG combined. These distinctions matter less to the E400 buyer who, while mindful of costs, prioritizes performance and open-air enjoyment along with the brand reputation. For a broader look at all Mercedes Benz fuel economy data, see our brand page here.

Tips to maximize efficiency

Adopt a smooth and anticipatory driving style. Avoid abrupt acceleration and braking. The E400’s engine produces ample torque, allowing you to accelerate gently while still keeping pace with traffic. Look ahead and anticipate traffic flow to minimize unnecessary braking and maximize momentum. This alone can significantly improve your fuel consumption.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, forcing the engine to work harder and burn more fuel. Regularly check your tire pressure against the manufacturer’s recommendations, usually found on a sticker inside the driver’s side doorjamb. Consistent tire maintenance is key.

Minimize unnecessary weight. Carrying around extra cargo in the trunk adds weight and reduces fuel efficiency. Remove any items you don’t need, such as golf clubs, tools, or other bulky objects. A lighter car requires less energy to accelerate and maintain speed.

Take advantage of the E400’s driving modes. The car likely has an “Eco” or “Comfort” mode that optimizes engine and transmission settings for fuel efficiency. Select this mode for everyday driving, especially in moderate to heavy traffic. Sport mode unleashes the full potential of the engine but does so at the expense of fuel economy.