21 MPG combined isn’t going to win any awards, but for the 2017 Cadillac CT6 equipped with all-wheel drive and the 3.6L V6, it represents a calculated tradeoff. This isn’t a car aimed at hypermilers; it’s a full-size luxury sedan intended for executives and those who prioritize comfort, space, and a smooth ride over outright fuel savings, all while maintaining all-weather confidence. The CT6 buyer understands this balance and accepts it as part of the ownership experience.

City and highway performance

The EPA estimates provide more detail. An 18 MPG city rating reflects the engine’s work in stop-and-go conditions. The all-wheel-drive system also adds weight and slightly increased frictional losses compared to a RWD configuration, impacting city MPG. On the open road, the CT6 AWD 3.6L performs better, achieving 27 MPG on the highway. The eight-speed automatic transmission allows the engine to cruise at lower RPMs at higher speeds, contributing to the improved efficiency. This difference between city and highway figures highlights the CT6’s suitability for longer commutes and road trips where its size, comfort, and refinement can be fully appreciated.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,100 for the 2017 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. The calculation also uses the national average fuel price at the time of the EPA’s testing. Keep in mind that your actual fuel costs may vary significantly depending on your driving habits, local fuel prices, and the specific conditions in which you operate the vehicle. Someone who primarily drives in congested city traffic will spend more than the EPA estimate, while someone who takes frequent long highway trips with consistently low fuel prices may spend less.

Real-world expectations

While the EPA provides a standardized benchmark, real-world fuel economy often deviates. Factors like driving style, traffic conditions, maintenance, and even tire pressure can influence MPG. Aggressive acceleration, frequent hard braking, and extended idling will all negatively impact fuel efficiency. Regular maintenance, including timely oil changes, air filter replacements, and properly inflated tires, helps the engine operate at peak efficiency. The CT6’s trip computer offers a running average of fuel economy, allowing drivers to monitor their consumption and adjust their habits accordingly.

How it compares

Compared to its competitors, the 2017 Cadillac CT6 AWD 3.6L sits in the expected range for a large luxury sedan. For example, the similarly equipped BMW 540i xDrive, with its 3.0L turbo six-cylinder, achieves an EPA-estimated 23 MPG combined. The Mercedes-Benz E300 4MATIC, with its smaller 2.0L turbo four-cylinder, boasts a slightly better 25 MPG combined. An Audi A6 2.0T quattro achieves 27 MPG combined. These differences are meaningful, but the CT6 isn’t directly competing to be the most frugal. The CT6 buyer is often prioritizing interior space, styling, or brand loyalty, understanding that a slight fuel economy penalty is part of the package. To see all Cadillac fuel economy data, visit our Cadillac brand page. You can also view CT6 MPG across all years to see fuel economy trends.

Tips to maximize efficiency

Optimize your driving style for efficiency. Avoid excessive acceleration and hard braking, opting for smooth and gradual inputs. Anticipate traffic flow and maintain a consistent speed whenever possible to minimize the need for constant speed adjustments.

Ensure your CT6 is properly maintained. Regular oil changes with the correct synthetic oil grade, along with timely air filter replacements, contribute to optimal engine performance and efficiency. Check tire pressures regularly and maintain them at the recommended levels, as underinflated tires increase rolling resistance and reduce fuel economy.

Reduce unnecessary weight in the vehicle. Remove any items from the trunk or rear seats that aren’t essential, as added weight directly impacts fuel consumption. Every extra pound requires more energy to accelerate and maintain speed, diminishing overall MPG.

Use cruise control on the highway. Maintaining a consistent speed minimizes unnecessary throttle adjustments, leading to improved fuel economy. However, use cruise control carefully in hilly terrain, as the system may downshift aggressively to maintain speed, negating some of the efficiency benefits.