21 MPG combined isn’t going to win any awards, but it’s the cost for the 2018 Cadillac CT6 AWD 3.6L, a large luxury sedan that prioritizes smooth power delivery and a spacious cabin over outright fuel efficiency. This isn’t a car for hypermilers; it’s for executives who want a comfortable and confident ride, regardless of the weather, and who are willing to accept middling fuel economy as a trade-off.

City and highway performance

The EPA estimates 18 MPG in the city and 27 MPG on the highway for the 2018 Cadillac CT6 with its all-wheel-drive system and naturally aspirated 3.6-liter V6 engine. The city figure reflects the engine’s need to work harder in stop-and-go traffic, and the AWD system’s constant engagement adds further resistance. The highway number demonstrates the efficiency gains possible when cruising at a steady speed. The eight-speed automatic transmission helps keep the engine in its optimal rev range, contributing to the relatively respectable highway MPG. These figures are a direct result of the vehicle’s hefty curb weight and all-wheel drive system, these both demand more energy to accelerate and maintain speed.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,100 for the 2018 Cadillac CT6 AWD 3.6L. This figure is based on driving 15,000 miles per year, with 55% of those miles driven in the city and 45% on the highway, using national average fuel prices. It’s a useful benchmark, but remember that your actual fuel costs will vary depending on your driving habits, local fuel prices, and the type of fuel you use. If you frequently engage in aggressive driving or spend a significant amount of time in heavy traffic, you can expect to exceed this estimate. Those who primarily drive on the highway and practice fuel-efficient driving techniques may spend less than $2,100 annually.

Real-world expectations

While the EPA estimates provide a standardized comparison tool, real-world MPG often deviates. Factors such as driving style, road conditions, and even tire pressure can influence fuel economy. Expect that 21 MPG combined to fluctuate. Aggressive acceleration and frequent braking can significantly decrease fuel efficiency, especially in the city.

Gentle acceleration, anticipating traffic flow, and maintaining a steady speed on the highway can help achieve, or even slightly exceed, the EPA estimates. The car’s overall weight plays a significant role as well; carrying extra cargo regularly will impact fuel consumption. The CT6 MPG across all years is dependent on how and where you drive.

How it compares

Compared to its competitors, the 2018 Cadillac CT6 AWD 3.6L sits somewhere in the middle of the pack in terms of fuel economy. For instance, the BMW 540i xDrive, with its turbocharged inline-six, achieves a slightly better 23 MPG combined. The Mercedes-Benz E450 4MATIC manages a similar 23 MPG combined, also thanks to its turbocharged engine. An Acura RLX, with its hybrid powertrain, easily surpasses the CT6 at 29 MPG combined. However, the CT6 offers a significantly lower purchase price than either the BMW or Mercedes, which can offset the slightly higher fuel costs. A buyer considering the CT6 may be willing to sacrifice a few MPGs for a more accessible price point, a typically American sense of luxury, and styling that breaks from the German mold. Reviewing all Cadillac fuel economy data can help put the CT6 in perspective next to others in its family.

Tips to maximize efficiency

Use the CT6’s Eco mode. This setting adjusts the engine and transmission for optimal fuel efficiency, softening throttle response and shifting to higher gears sooner. While it might slightly reduce responsiveness, it can make a noticeable difference in fuel consumption, especially during city driving.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel. Check your tire pressure regularly, especially before long trips, and inflate them to the recommended pressure listed on the doorjamb.

Avoid excessive idling. If you anticipate being stopped for more than a minute, turn off the engine. Modern engines are designed to restart quickly and efficiently, and idling wastes fuel unnecessarily. This is especially beneficial in city driving, where frequent stops are common.

Anticipate traffic and drive smoothly. Avoid sudden acceleration and braking, as these actions consume significantly more fuel. By anticipating traffic flow and maintaining a steady speed, you can minimize fuel consumption and improve overall efficiency.

Lighten your load. Carrying unnecessary weight in your trunk or backseat reduces fuel economy. Remove any items you don’t need, especially heavy objects. Reducing the overall weight of the vehicle allows the engine to work less hard, resulting in less gas use.