22 MPG combined accurately positions the 20025 Lexus IS 300 AWD 3.5L 6-cyl not as a fuel-sipper, but as a strong, luxurious compact sport sedan prioritizing all-weather traction and a smooth, naturally aspirated powertrain. This is a car for buyers who appreciate the traditional Lexus virtues of refinement and reliability, coupled with the confidence of all-wheel drive, and who view its fuel economy as a perfectly acceptable trade-off for the advantages of a proven six-cylinder engine rather than a turbocharged four.

City and highway performance

The EPA rates the IS 300 AWD at 19 MPG in the city and 26 MPG on the highway. In urban environments, that 19 MPG figure is directly because of the 3.5-liter V6 working through an automatic transmission. Stop-and-go traffic, frequent acceleration from standstill, and the constant demands of moving a nearly 3,800-pound sedan with all four wheels engaged naturally result in higher fuel consumption. This isn’t a powertrain designed for aggressive regenerative braking or highly efficient low-speed cruising; it’s engineered for smooth, linear power delivery. On the highway, the 26 MPG is solid for the class and powertrain configuration. The IS 300’s S6 automatic transmission, while not as advanced as some competitors’ 8- or 9-speed units, is well-matched to the engine’s torque curve, keeping RPMs reasonable at cruising speeds. However, the all-wheel-drive system inherently introduces some parasitic drag, preventing the highway number from climbing into the high 20s or low 30s seen in some rear-wheel-drive or smaller-engined rivals.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2025 Lexus IS 300 AWD 3.5L 6-cyl at $2,650. This figure is derived assuming 15,000 miles of driving per year, split between city and highway conditions, and based on national average fuel prices for its recommended fuel type. It’s a straightforward calculation reflecting the combined 22 MPG rating. For the buyer of the IS 300 AWD, this annual cost is generally considered reasonable. They aren’t seeking the absolute cheapest car to run, but rather a reliable, comfortable, and dynamically capable luxury sedan. The $2,650 is seen as part of the overall cost of ownership for a premium vehicle that delivers on its promises of quality and performance, without venturing into the territory of high-performance vehicles with significantly larger fuel bills.

Real-world expectations

Drivers can generally expect the 2025 IS 300 AWD to achieve its EPA estimates with diligent driving. However, spirited driving, which the naturally aspirated V6 encourages, will quickly see the MPG drop. The V6 delivers its power smoothly and linearly, making it easy to tap into its reserves, which consumes more fuel. Similarly, extensive use of the car’s Sport or Sport+ driving modes, which adjust throttle response and transmission shift points for more aggressive performance, will inevitably lower fuel economy below the 22 MPG combined figure. Frequent short trips, especially in cold weather, will also impact efficiency, as the engine takes longer to reach optimal operating temperature. Conversely, consistent highway cruising at moderate speeds, using cruise control, can often push the highway figure slightly higher than the EPA’s 26 MPG. The IS 300 is a car that responds to the driver’s input, and that includes its fuel consumption; drive it hard, and it will drink more. Drive it gently, and it will reward with its rated economy.

How it compares

Comparing the 2025 Lexus IS 300 AWD to its direct rivals reveals its unique position in the market, particularly regarding its powertrain and its effect on fuel economy. For instance, the BMW 330i xDrive, a common cross-shop, uses a turbocharged 2.0-liter 4-cylinder engine. It boasts 25 MPG city, 34 MPG highway, and 29 MPG combined. This significant difference (7 MPG combined) stems from the smaller, forced-induction engine design and generally more advanced transmission technology. Another competitor, the Mercedes-Benz C 300 4MATIC Sedan, also employs a turbocharged 2.0-liter 4-cylinder, yielding 23 MPG city, 33 MPG highway, and 27 MPG combined. Again, the 5 MPG combined difference highlights the efficiency advantage of modern turbocharged fours. Even the Audi A4 quattro, with its 2.0-liter turbo, achieves 24 MPG city, 31 MPG highway, and 27 MPG combined. The buyer choosing the IS 300 AWD over these rivals is consciously opting for the visceral, linear power delivery and legendary reliability of Lexus’s naturally aspirated V6, and a mature, proven platform over cutting-edge efficiency. They accept the fuel economy trade-off for a different driving character and perhaps a lower long-term maintenance cost. For full details on all Lexus fuel economy data, our comprehensive database has you covered, or specifically for this model, you can check IS MPG across all years.

Tips to maximize efficiency

To get the most out of your IS 300 AWD, consider a slightly lighter foot on the throttle. The V6 is eager but smooth; avoid unnecessary hard acceleration, especially from a standstill. This smooth input will keep the transmission from downshifting abruptly and reduce fuel consumption.

Maintain consistent highway speeds. While the IS 300 offers ample passing power, varying your speed frequently on long trips can negate the benefits of continuous cruising. Engage cruise control when appropriate to hold a steady pace.

Keep your tires properly inflated. Underinflated tires increase rolling resistance, forcing the engine to work harder. Check your tire pressures regularly, especially when temperatures change significantly, to ensure they match the manufacturer’s recommended specifications.

Avoid carrying excessive weight. While the IS 300 is a substantial vehicle, extra cargo in the trunk or rear seats adds ballast that the engine must propel, slightly impacting fuel economy. Remove unnecessary items to lighten the load.

Adhere to the recommended maintenance schedule. Regular oil changes, air filter replacements, and spark plug checks ensure the engine operates at peak efficiency. A well-maintained engine is an efficient engine, burning fuel optimally.