Not that Im aware of. Nissan has spent a ton of money getting the most power and mileage out of their cars, if it was possible to get more MPG without hurting performance they would do it. Be sure your tires are inflated properly, and when itis time to replace them, they make tires that go to 50psi, instead of 35 or 44. It gives less rolling resistance. Most mileage improvements are in driving habits, easy throttle off the light, easy acceleration.