26 MPG combined is a perfectly acceptable fuel economy figure for the 2021 Mercedes-Benz CLS450. It’s not aiming for Prius-level efficiency, and it shouldn’t. The CLS450 exists for a specific buyer: someone who prioritizes style, technology, and good performance in a refined package. They want the presence and luxury of a Mercedes-Benz sedan, wrapped in a more expressive, coupe-like design. Fuel economy is a consideration, but likely not the deciding factor.

City and highway performance

The EPA estimates of 23 MPG in the city and 30 MPG on the highway are reasonable expectations for the CLS450. The city figure reflects the engine’s responsiveness and the demands of stop-and-go traffic, while the highway number showcases the benefits of the nine-speed automatic transmission. This transmission keeps the engine in its sweet spot for efficiency at higher speeds, contributing to a more relaxed and economical long-distance cruise. Note that driving style and terrain can significantly impact fuel economy, particularly on the city MPG.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 Mercedes-Benz CLS450 at $2,250. This figure is based on driving 15,000 miles per year, with a mix of city and highway driving, and using the national average fuel prices at the time of calculation. It’s a useful benchmark, but individual fuel costs can vary significantly based on driving habits, local fuel prices, and the grade of fuel used. Mercedes-Benz recommends premium fuel for optimal performance, which typically commands a higher price.

Real-world expectations

While the EPA estimates provide a useful baseline, real-world fuel economy can vary. The CLS450’s turbocharged 3.0-liter inline-six encourages spirited driving, and frequent use of its available power will certainly impact fuel consumption. Aggressive acceleration, hard braking, and prolonged idling can all lower your MPG. Conversely, a more conservative driving style, prioritizing smooth acceleration and maintaining consistent speeds, can help you achieve or even surpass the EPA estimates. Terrain also plays a role. Hilly or mountainous routes will likely result in lower fuel economy compared to flat, open highways. Drivers who frequently engage the “Sport” or “Sport+” driving modes should expect a reduction in MPG.

How it compares

Compared to its competitors, the 2021 CLS450’s fuel economy is generally competitive within its class. For example, the BMW 840i Gran Coupe, also with a turbocharged inline-six, achieves a similar 25 MPG combined rating. The Audi A7, with its available supercharged V6, typically falls within the same range, hovering around 24 MPG combined. Stepping up to models with larger V8 engines, such as the Mercedes-AMG CLS53, sees a noticeable decrease in fuel economy, often dipping below 22 MPG combined. If lower fuel costs are a top priority alongside the four-door coupe bodystyle, it’s tough to do better than the CLS450 without sacrificing a significant amount of performance or moving into a completely different vehicle segment. Those researching all Mercedes Benz fuel economy data will find this to be a reasonable choice among the brand’s offerings. And for those specifically interested in CLS450 MPG across all years, the 2021 model stacks up well against earlier iterations.

Tips to maximize efficiency

Take it easy on the accelerator. The CLS450’s 362 horsepower is tempting to unleash, but gentle acceleration and anticipating traffic flow can significantly reduce fuel consumption. Avoid hard starts and abrupt stops whenever possible to maximize your MPG.

Maintain proper tire inflation. Underinflated tires create more rolling resistance, which forces the engine to work harder and burns more fuel. Check your tire pressure regularly and inflate them to the recommended levels, which can be found on a sticker inside the driver’s side doorjamb.

Use cruise control on the highway. Maintaining a consistent speed on long highway drives is key, and cruise control helps you do that. It eliminates the fluctuations in speed that often occur when driving manually, leading to improved fuel efficiency.

Minimize idling time. Idling wastes fuel. If you’re stopped for more than a minute or two, turn off the engine. Modern cars are designed to restart quickly and efficiently, so there’s no need to let the engine run unnecessarily.

Keep up with scheduled maintenance. A well-maintained engine is an efficient engine. Follow the recommended maintenance schedule in your owner’s manual, including regular oil changes, air filter replacements, and spark plug inspections, to ensure optimal performance and fuel economy.