What is not so cool, is that for a $2500 upcharge on the Malibu, or $3500 on the Aura, you can look forward to an improvement in your gas milage of exactly 2 MPG. That is awesome. No wonder Toyota, Honda, and even Ford are actually selling hybrids. They actually deliver some benefit to the owner, and the planet. Even Nissan is getting into the act with a limited number of Altimas, with parts bought from Toyota.
If GM is going to bother, they should be able to do better than a hybrid system that gets you 32 MPG vs. 30MPG delivered by their 4-banger.
Hell, I've said it before, but my '95 Volvo gets 30 on the highway if you treat it nice. If you really want to save money, you can buy an older (and I mean ~1997) Volvo sedan with 100K miles (that means another 100K miles left in it) for about 2 grand. Get the wagon if that makes your pants tight. Think of all that metal and other resources you'd be re-using. That in its own way is pretty "green". And, you save some green on your next car purchase.
If you want to save the planet, well, thats not so cheap. Just don't throw money away on GM hybrids.