25 MPG combined is not why someone buys a 2021 Mercedes-Benz E450 Convertible. Let’s be clear. This is a car for sunshine, for weekend getaways, for making a statement. It’s not for hypermiling. While a Prius driver might scoff, appreciating the E450 Convertible is about understanding its priorities and accepting that fuel efficiency plays a supporting role to open-air thrills and effortless power.

City and highway performance

The EPA estimates the E450 Convertible at 23 MPG in the city and 30 MPG on the highway. The spread isn’t huge, which reflects the smooth, consistent power delivery of the 3.0L turbocharged inline-six engine. Around town, the nine-speed automatic keeps the engine in its sweet spot, providing ample torque for confident acceleration. On the open road, 30 MPG is respectable for a luxury convertible. The highway figure is very speed-dependent; sustained high-speed cruising will likely see that number dip. The E450 Convertible doesn’t punish you excessively for enjoying its performance, but it definitely isn’t shy about asking for premium fuel in return.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 Mercedes-Benz E450 Convertible at $2,300 per year. This calculation is based on driving 15,000 miles per year and using the national average fuel prices. Given the E450’s penchant for premium gasoline, that $2,300 figure represents a significant slice of the ownership pie. It’s a number worth considering alongside the car’s hefty price tag and luxury features, as it contributes meaningfully to the overall cost of putting this car in your garage.

Real-world expectations

Don’t expect to consistently match the EPA’s figures in real-world driving. The allure of the E450 lies in its responsive engine and sporty demeanor, and it’s tempting to exploit that performance. A lead foot will inevitably lead to lower MPG. If your typical driving involves mostly short trips in stop-and-go traffic, the city MPG will likely be considerably lower than the official estimate. However, if you frequently embark on long highway cruises at moderate speeds, you might see a slight improvement over the 30 MPG rating. The important thing is to understand that your own driving habits will heavily influence the actual fuel consumption.

How it compares

The BMW 4 Series Convertible (specifically the M440i) with its turbocharged inline-six is a direct competitor, and it achieves roughly similar fuel economy numbers, floating around 25 MPG combined. The Audi S5 Cabriolet, with its turbocharged V6, generally scores a bit lower, often closer to 23 MPG combined. While these marginal differences exist, most buyers in this segment prioritize other aspects like styling, performance, and brand cachet. Someone considering the E450 Convertible isn’t necessarily cross-shopping it against a hyper-efficient hybrid; they’re likely comparing it to other luxury convertibles where overall fuel economy is secondary to the driving experience and prestige. Review all Mercedes Benz fuel economy data to see how the E450 compares to the rest of the lineup and browse E450 MPG across all years.

Tips to maximize efficiency

While efficiency might not be the primary goal of driving an E450 Convertible, there are still ways to optimize fuel consumption without sacrificing too much enjoyment. One simple strategy is to pay attention to your throttle inputs. Smooth, gradual acceleration consumes less fuel than aggressive starts and stops. Try to anticipate traffic flow and maintain a steady speed whenever possible.

Take advantage of the car’s driving modes. The E450 typically offers an “Eco” or “Comfort” mode that adjusts the engine and transmission mapping for improved fuel efficiency. This mode might slightly reduce throttle response, but it can make a noticeable difference on longer trips.

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

Avoid unnecessary weight in the vehicle. Extra cargo adds to the car’s load, which in turn increases fuel consumption. Remove any items from the trunk or backseat that you don’t need on a regular basis.