Owners of the 2015 Subaru Legacy AWD with the 3.6L six-cylinder engine average 23 MPG combined. This isn’t a class-leading figure, but it’s a trade-off for drivers who prioritize all-weather confidence and the smooth power of a larger engine over maximizing fuel efficiency in a mid-size sedan. They likely want a sedan that feels capable in bad weather, and they are willing to pay extra for it.

City and highway performance

The EPA estimates of 20 MPG in the city and 28 MPG on the highway reveal the Legacy 3.6R’s good and bad points. The city figure reflects the higher fuel consumption from stop-and-go driving, made worse by the constant engagement of the all-wheel-drive system. That drivetrain reduces power, and therefore fuel, even when traction isn’t an issue. On the open road, at a steady cruising speed, the 28 MPG highway figure is more respectable, but it still lags behind some of the Legacy’s more fuel-efficient competitors. The automatic transmission (AV-S6) is programmed for smooth shifts and generally keeps the engine in its optimal range for power, but it’s not designed to squeeze every last drop of fuel from the tank. The calibration favors confident acceleration and predictable performance.

Annual fuel cost

The estimated annual fuel cost for the 2015 Subaru Legacy 3.6R AWD is $1,900, according to the EPA. This figure is based on driving 15,000 miles per year, using a national average for fuel prices, but this is only an estimate. Your actual fuel costs will vary depending on your driving habits, the type of driving you do (city vs. highway), and local fuel prices. Drivers who frequently experience heavy traffic or drive aggressively will likely spend more. Those who primarily drive on the highway at moderate speeds might be able to improve upon it slightly. It’s a helpful starting point for budgeting, but not a guaranteed number.

Real-world expectations

While the EPA provides standardized testing, real-world mileage often differs from the official numbers. Many 2015 Legacy 3.6R owners report figures slightly below the EPA averages, especially in mixed driving conditions. You should expect combined mileage closer to the low 20s if you regularly encounter city traffic or engage the all-wheel-drive system in challenging conditions. Highway mileage often aligns more closely with the EPA estimate, provided you maintain consistent speeds and avoid aggressive acceleration. Driving style is a major factor; aggressive driving will significantly reduce fuel economy.

How it compares

The 2015 Subaru Legacy 3.6R AWD isn’t a leader in fuel economy; its appeal is based on other factors. A 2015 Toyota Camry with its base 2.5L four-cylinder engine achieves an EPA-estimated 28 MPG combined. That’s a substantial improvement, but you lose the Legacy’s all-wheel drive and the refined power of the six-cylinder engine. The Honda Accord, another competitor, achieves similar fuel economy figures with its four-cylinder engine and also lacks all-wheel drive. Even a V6 Accord from the same year posts a combined 25 MPG, a notable advantage. To get all all Subaru fuel economy data in one place, check out our make page. To see LEGACY MPG across all years, check out that model’s page on our site.

Tips to maximize efficiency

The 2015 Legacy 3.6R AWD isn’t known for great fuel economy, but you can still take steps to improve your mileage. Regular maintenance is key. Make sure your tires are properly inflated, the air filter is clean, and the engine is running smoothly. A well-maintained engine is an efficient engine.

Avoid hard acceleration and braking. The Legacy’s all-wheel-drive system provides traction and stability, but it doesn’t replace smooth driving. Anticipate traffic conditions and avoid unnecessary bursts of speed. Gradual acceleration and smooth braking will significantly reduce fuel consumption.

Minimize idling. Letting your engine idle for extended periods wastes fuel. If you’re stopped for more than a minute, turn off the engine. Modern engines are designed to restart quickly and efficiently, and the fuel savings will add up over time.

Use cruise control on the highway when possible. Cruise control helps maintain a consistent speed, which reduces fuel consumption compared to fluctuating speeds caused by manual throttle control. This is especially effective on long highway drives where you can maintain a constant speed.

Consider using fuel additives sparingly. Some additives claim to improve fuel economy, but their effectiveness can vary. Research any additives thoroughly before using them and be careful of exaggerated claims. A healthy engine and mindful driving are generally more effective than relying on additives.