21 MPG combined isn’t going to win any awards for lower fuel costs, but it accurately reflects the compromise in the 2020 Cadillac CT6 AWD 3.6L. This isn’t a hybrid designed to save fuel; it’s a full-size luxury sedan designed to deliver a smooth, comfortable, and confident driving experience, and the fuel economy reflects that priority. The buyers of this car aren’t primarily focused on maximizing MPGs; they value space, comfort, prestige, and all-weather capability, understanding that those attributes come with a cost at the pump.

City and highway performance

The EPA estimates are 18 MPG in the city and 27 MPG on the highway. In urban environments, the CT6’s weight and the stop-and-go nature of city driving contribute to the lower fuel economy figure. The 3.6L V6 works harder overcoming inertia from a standstill, and even with cylinder deactivation technology, idling consumes fuel. On the highway, the CT6 fares better.

The 10-speed automatic transmission helps keep the engine in its most efficient range at cruising speeds. The aerodynamic design of the CT6 also plays a role in reducing drag and improving fuel efficiency at higher speeds. Regular highway trips will push your overall average closer to that 27 MPG mark.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2020 Cadillac CT6 AWD 3.6L at $2,100. This figure is calculated based on driving 15,000 miles per year, with a 55/45 split between city and highway miles, using the national average fuel price at the time of calculation. Individual spending will vary based on driving habits, local fuel prices, and the proportion of city versus highway driving.

Those who log more highway miles and live in areas with lower fuel costs will likely spend less. Conversely, drivers with a lead foot in expensive metropolitan areas will almost certainly exceed that $2,100 mark.

Real-world expectations

While the EPA estimates provide a standardized baseline, real-world fuel economy often deviates. Expect variations of 1-3 MPG from those figures depending on driving style, terrain, and vehicle maintenance. Aggressive acceleration, frequent hard braking, and consistent use of the CT6’s performance-oriented driving modes will quickly diminish fuel economy. Uphill driving, especially with a loaded vehicle, also reduces efficiency.

Regular maintenance, including timely oil changes, tire inflation, and air filter replacements, can help maintain optimal fuel economy over the long term. A well-maintained CT6 driven conservatively on relatively flat terrain should come closer to matching the EPA estimates.

How it compares

Compared to other large luxury sedans with all-wheel drive, the 2020 CT6’s fuel economy is generally average. The BMW 540i xDrive, for example, achieves a similar 25 MPG combined. An Audi A6 55 TFSI quattro is also in the same ballpark, hovering around 24 MPG combined. The Mercedes-Benz E450 4MATIC isn’t far off, either. This suggests that the buyer in this segment has to accept a certain level of fuel consumption penalty in exchange for the comfort and technology one expects.

Those focused on maximizing efficiency might consider hybrid options like the Lexus ES 300h (44 MPG combined), but those sacrifices come with a completely different driving experience that isn’t always satisfactory. If one wants a traditional luxury sedan, however, one is likely to find all Cadillac fuel economy data competitive with its rivals, especially when considering performance capability.

Tips to maximize efficiency

Optimize your driving habits. Avoid rapid acceleration and hard braking. Anticipate traffic flow and maintain a consistent speed whenever possible. Using cruise control on the highway helps minimize unnecessary speed fluctuations, leading to better fuel efficiency.

Ensure your tires are properly inflated. Under-inflated tires increase rolling resistance, forcing the engine to work harder and consume more fuel. Check your tire pressure regularly, using the recommended PSI found on the sticker inside the driver’s side doorjamb.

Reduce unnecessary weight. Carrying excessive cargo in the trunk or backseat adds weight to the vehicle, reducing fuel economy. Remove any items you don’t need for your daily commute. Even removing a few heavy items can make a noticeable difference, especially around town. Consider that if you’ve owned a CT6 across multiple years, your driving habits might have changed since the last time you compared CT6 MPG across all years.

Use the appropriate driving mode. The CT6 offers different driving modes, which can impact fuel economy. Select the “Tour” or “Eco” mode for everyday driving to prioritize fuel efficiency over performance. Sport mode will cause the drivetrain to draw from its performance reserves, at the cost of efficiency.

Keep up with routine maintenance. Regular oil changes, air filter replacements, and spark plug maintenance are important for optimal engine performance and fuel efficiency. Following the manufacturer’s recommended maintenance schedule will help your CT6 run smoothly and efficiently for years to come.