Absolutely! A pound off the drivetrain is WAY more efficient than a pound of the entire car. You would be hard pressed to save 7 pounds in an aluminum hood and have structural rigidity.A savings of a few pounds on a hood or the almost 20lbs savings in the rims and the reduction in rolling mass....seems like a no brainer to me!!
More information here: 2011 Chevrolet Cruze – Powertrain and Chassis details [Archive] - CleanMPG ForumsThe new Ecotec 1.4L turbo engine is built on a strong, low-mass foundation that supports its high-performance, high-efficiency attributes. Details on key features include:
Cylinder block – It is made of strong gray cast iron, with five reinforced main bearings. The block offers excellent thermal properties that suit the cylinder pressure and loads generated by a turbocharger system. To minimize weight, it features hollow-frame construction, making it about 20 percent lighter than a conventional casting. The block also incorporates a gray cast iron bedplate that helps reduce engine vibration.