18 MPG combined isn’t going to win any awards, but for the 2015 Cadillac CTS Sedan 3.6L, it’s the price of admission. This isn’t a car for penny-pinchers. This is a car chosen by those who value American luxury, sharp styling, and a responsive driving experience. They appreciate performance and presence, and they’re willing to live with fuel economy that reflects those priorities. The CTS delivers a distinctive alternative to the ubiquitous German sedans, and for a certain type of driver, that distinction is worth more than a few extra miles per gallon.

City and highway performance

The EPA estimates for the 2015 Cadillac CTS Sedan equipped with the 3.6L V6 and 8-speed automatic transmission break down to 16 MPG in the city and 24 MPG on the highway. The city figure reflects the reality of stop-and-go traffic, where the CTS’s weight and lively engine work against fuel efficiency. The highway number is more respectable, showcasing the benefit of the smooth-shifting 8-speed and the engine’s ability to cruise comfortably at higher speeds. However, aggressive driving, even on the open road, will quickly pull that highway figure down. Remember these are estimates, your actual mileage will vary based on how and where you drive.

Annual fuel cost

According to the EPA, the annual fuel cost for this particular CTS configuration is $3,200. This figure is based on driving 15,000 miles per year and using national average fuel prices. It’s a useful benchmark, but keep in mind that fuel prices fluctuate significantly depending on location and time of year, and your personal driving habits, such as frequent short trips or aggressive acceleration, will directly affect how closely your real-world fuel expenses align with this $3,200 estimate. Consider it a starting point for budgeting, not a guaranteed outcome.

Real-world expectations

While the EPA provides a standardized baseline, consider real-world owner experiences. Some drivers report highway fuel economy figures close to the EPA estimate of 24 MPG when driven conservatively. However, combined MPG often sits closer to 17 MPG, slightly below the EPA’s stated 18 MPG. This discrepancy highlights the impact of driving style and conditions. Lead-footed drivers and those commonly stuck in heavy traffic will see lower numbers, while those who prioritize smooth acceleration and consistent speeds will likely achieve results closer to the official estimates. Before buying, you should always check CTS MPG across all years to get a general picture of driver experiences.

How it compares

The 2015 Cadillac CTS 3.6L’s fuel economy lags behind some of its key competitors. For example, the BMW 535i from the same year, with its turbocharged 3.0-liter inline-six, achieves a combined EPA rating of 23 MPG. The Mercedes-Benz E400, with its turbocharged 3.0-liter V6, manages about 24 MPG combined. Even the Audi A6 3.0T, with its supercharged V6 and standard all-wheel drive, gets around 24 MPG combined. The CTS buyer may sacrifice a few MPGs compared to these German rivals, but they often do so for the Cadillac’s unique design, distinct driving dynamics, and a feeling of homegrown luxury. For all Cadillac models, see all Cadillac fuel economy data.

Tips to maximize efficiency

Use a light foot on the accelerator. The CTS 3.6L is responsive, but aggressive acceleration burns fuel quickly. Smooth, gradual acceleration will significantly improve your MPG, particularly in city driving. Anticipate traffic flow and avoid unnecessary braking and acceleration.

Ensure your tires are properly inflated. Underinflated tires increase rolling resistance, which negatively impacts fuel economy. Check your tire pressure regularly and inflate them to the recommended level, typically found on a sticker inside the driver’s side door jamb. Consider using the “Eco” drive mode if equipped. This mode typically adjusts the throttle response and transmission shift points to prioritize fuel efficiency over performance.

Avoid excessive idling. If you’re stopped for more than a minute, turn off the engine. Modern cars like the CTS are designed to restart quickly and reliably, and prolonged idling wastes fuel unnecessarily.

Keep up with regular maintenance. A well-maintained engine runs more efficiently. Follow the manufacturer’s recommended maintenance schedule, including oil changes, air filter replacements, and spark plug inspections. Clogged air filters and old spark plugs can negatively impact fuel economy.