23 MPG combined is unlikely to be the deciding factor for anyone considering the 2020 Mercedes-Benz E450 Convertible with its smooth 3.0L inline-six. This isn’t a car bought for practicality; it’s a statement. It’s about open-air motoring, comfortable seating, and effortless performance. While owners appreciate reasonable fuel consumption, it’s far down the list of priorities compared to the experience this car delivers.

City and highway performance

The EPA estimates for the E450 Convertible break down to 20 MPG in the city and 27 MPG on the highway. The small difference between city and highway figures shows the advanced 9-speed automatic transmission is doing its job, keeping the engine in its power band whether navigating urban sprawl or cruising at speed. Buyers should expect the highway number to be achievable on longer road trips, while city driving, especially in congested areas, will likely yield results closer to, or even below, the 20 MPG mark. This isn’t egregious for a car with this much power, but it’s worth keeping in mind if you frequently find yourself stuck in stop-and-go traffic.

Annual fuel cost

The EPA calculates the annual fuel cost for the 2020 Mercedes-Benz E450 Convertible at exactly $2,500. This figure is based on driving 15,000 miles per year, with a mix of city and highway driving, using national average fuel prices. It’s a helpful benchmark, but your actual expenditure will depend on your driving habits, local fuel prices, and even the grade of gasoline you choose to use. Using premium fuel, as recommended for optimal performance, will further increase the annual cost.

Real-world expectations

While the EPA estimates provide a solid baseline, real-world fuel economy can vary. Aggressive driving, frequent use of the car’s acceleration, and extended idling will all negatively impact your MPG. A gentle right foot and consistent highway speeds will likely yield figures closer to or slightly above the EPA’s estimates. Owners often report a range between 21 and 25 MPG in mixed driving, highlighting how driving style affects fuel efficiency. Keeping your tires properly inflated and adhering to the recommended maintenance schedule will also help maintain good fuel economy.

How it compares

The E450 Convertible’s fuel economy places it among its competitors. The BMW 440i Convertible, for example, delivers a similar experience and achieves an EPA-estimated 25 MPG combined. The Audi S5 Cabriolet, with its turbocharged V6 and standard quattro all-wheel drive, comes in slightly lower at 22 MPG combined. These differences are often secondary to the overall driving experience and brand preference for buyers in this segment. For those considering higher performance models, like the Mercedes–AMG C43 Convertible, fuel economy drops several MPG. A prospective buyer might review all Mercedes Benz fuel economy data before deciding on a purchase. And if the specific model that appeals to them is the E450, they might want to check historical E450 MPG across all years.

Tips to maximize efficiency

Take advantage of the E450’s driving modes. Selecting “Comfort” or “Eco” mode will change the engine and transmission settings for fuel efficiency, softening throttle response and encouraging earlier upshifts. These subtle adjustments can make a noticeable difference, especially in city driving.

The 9-speed automatic transmission is designed to keep the engine efficient. Avoid aggressive acceleration and let the transmission do its job. A smooth driving style will reward you with better fuel economy and a more relaxed driving experience.

Regularly check your tire pressure and ensure it matches the recommended specifications. Underinflated tires increase rolling resistance, negatively impacting fuel economy. A simple tire pressure check can make a difference.

Minimize idling. Modern engines don’t require extended warm-up periods, and idling wastes fuel. If you’re stopped for more than a minute or two, it’s more efficient to turn off the engine.

Plan your trips to avoid peak traffic times whenever possible. Stop-and-go traffic reduces fuel economy. By opting for less congested routes, even if they’re longer, you can save time and gas.