21 MPG combined isn’t going to win any awards, but it’s the price of admission for the 2018 Cadillac CT6 AWD 3.0L. This isn’t a car purchased by penny-pinchers obsessed with maximizing fuel efficiency. It’s a car for executives, for those who value a smooth ride, a quiet cabin, and the confidence of all-wheel drive. Fuel economy is a consideration, certainly, but it’s weighed against the benefits of a twin-turbocharged V6 and Cadillac’s distinct brand of American luxury.

City and highway performance

The EPA estimates the CT6 AWD 3.0L at 18 MPG in the city and 26 MPG on the highway. The city figure reflects the reality of stop-and-go traffic, the kind of driving where the engine’s start-stop system is most likely to engage.

The highway number, while respectable, is less impressive when you consider the CT6’s purpose as a long-distance cruiser. Drivers who frequently undertake extended highway journeys might find themselves wishing for slightly better fuel mileage from its 3.0L engine. The eight-speed automatic transmission generally performs well, but can occasionally hunt for gears, especially during rolling highway acceleration. A more decisive programming might improve fuel economy in these scenarios.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2018 Cadillac CT6 AWD 3.0L at $2,750. This figure is based on driving 15,000 miles per year and using national average fuel prices. Some drivers may spend more or less depending on their individual driving habits and the price of gasoline in their area.

While $2,750 represents a tangible expense, it’s important to contextualize this figure within the overall cost of owning and operating a luxury sedan. Insurance, maintenance, and depreciation all contribute to the total ownership experience, and the CT6’s fuel costs are just one piece of the puzzle.

Real-world expectations

While the EPA figures provide a useful benchmark, real-world fuel economy can vary significantly. Drivers who primarily drive in congested city environments are likely to see figures closer to or even slightly below the 18 MPG city rating. Conversely, those who spend most of their time on the open highway, maintaining a steady cruising speed, might achieve numbers closer to, or occasionally slightly above the EPA’s 26 MPG highway estimate.

Driving style has a big impact. Aggressive acceleration and frequent hard braking will negatively affect fuel economy, while a smoother, more deliberate driving style can help to maximize it. A well-maintained engine will always deliver better fuel economy. See CT6 MPG across all years data for further comparison.

How it compares

Compared to its competitors, the 2018 Cadillac CT6 AWD 3.0L lands in a middle-of-the-road position. The BMW 540i xDrive, for instance, achieves a slightly better 23 MPG combined. The Mercedes-Benz E450 4Matic also offers slightly better fuel economy at 23 MPG combined. However, the CT6 often undercuts these rivals in price, making its slightly lower fuel economy more palatable for some buyers. The Lexus GS 350 AWD lags behind with 22 MPG combined. Buyers cross-shopping these vehicles will likely weigh the CT6’s distinctive styling and generous features against its fuel consumption figures relative to these other models. For buyers who really want better fuel economy, they can see all Cadillac fuel economy data.

Tips to maximize efficiency

Take advantage of the start/stop system. The 2018 CT6 features an automatic start/stop system that shuts off the engine when the car is stopped, such as at a red light. Ensure this system is activated and allow it to function as intended. While it might feel unusual at first, it significantly reduces fuel consumption during city driving.

Monitor tire pressure regularly. Underinflated tires increase rolling resistance, which in turn reduces fuel economy. Check your tires at least once a month and inflate them to the recommended pressure listed on the sticker inside the driver’s side door jamb.

Use cruise control on the highway. Maintaining a consistent speed on the highway minimizes unnecessary acceleration and deceleration, which can help to improve fuel economy. The CT6’s adaptive cruise control system is especially useful for this purpose, automatically adjusting your speed to maintain a safe following distance from the vehicle ahead.

Avoid aggressive driving. Rapid acceleration, hard braking, and high speeds consume more fuel. Drive smoothly and anticipate traffic conditions to minimize these behaviors. The CT6’s twin-turbocharged V6 is tempting to unleash, but restraint will pay dividends at the pump.

Use Cadillac’s selectable drive modes. The CT6 offers different drive modes that can affect fuel economy. Use the “Tour” mode for everyday driving, as it optimizes fuel efficiency. Reserve the “Sport” mode for those occasions when you want to exploit the engine’s full performance potential, but be aware that it will reduce fuel economy.