Using regular unleaded in my non turbo 2.4L regal I'm getting 31-32 MPG on the highway and 25 around town thats with summer blend fuel. I started using non-ethenal fuel unfortunately it's only sold as a premium fuel so it's 1$+ from the regular. Slight increase in milage. Regular grade winter blend fuel the highway milage is 28-29MPG around town 21-22. The car has 15K on it so I use the non ethenol fuel to minimize water contamination when its sitting for extended periods.