Why would a bike feature a "carbon wrapped aluminum frame"? I saw a link to what appeared to be a Carbon bike on amazon.  The price was extremely lower than any carbon bike I had ever seen.  After reading a bit, it seems that the bike frame is really made of "carbon fibre wrapped aluminum". What advantages would wrapping an aluminum frame in carbon have compared to just a regular aluminum bike.  Is it just to get a carbon look bike more cheaply, or does it allow you to use a narrower aluminum frame, with carbon taking up some stress, creating a frame with a weight somewhere between carbon and aluminum?
That is purely marketing. It's a common ploy with components, but I've never seen it on an entire frame until now. Aluminum and carbon can be used in conjunction effectively, but not in this case. The carbon wrap on that bike is basically veneer. While Schwinn was once upon a time a well respected brand, they suffered a major fall from grace after going bankrupt. Their bikes, even their bike shop level bikes (i think they call them their "select" series bikes) target the budget market. They're not horrible, but they're not great either. The bike you posted a link to is no exception. One could argue that the combination of dissimilar materials would aid to vibration dampening, but that's really just more marketing jargon, at least in this case. That bike will still ride just like a full aluminum framed bike would. If you are considering that bike save yourself a few bucks and just go with a full aluminum frame.