Greetings, I own a 2014 chevy cruze with a 1.4 turbo and a 2013 Malibu with the 2.5 both DI engines. With much talk about carbon and such in DI engines is premium the way to go? I run premium in both engines, mostly Shell V poweer with an occasional Marathon or speedway stop all which claim to have 93 octane premium. The shell v power nets a consistent 35 MPG in the Malibu with other premiums only getting 32 MPG on average . My wife drives the Cruze and gets 35mpg as well but tends to idle the car alot before driving in the morning. The question to all this being is premium fuel a benefit in DI cars ?