I'll tell you what. From the Edmunds picks it is definitely longer and a little wider but it has not grown fat. A Camry, an Accord, a Passat, they are fat cars. I mean I don't have a problem with it but they do look very bloated compared to the 6. The 6 in the spy shots though wider and longer still maintains a sleek body like Audi does. The A6 is a large car but is still sleek, especially when you compare it to something like an Infiniti M.
The primary gauge for the new 6 was the altima/maxima. The new 6's dimensions are supposedly bigger in every aspect vs the latest model nissan alt/max. They are targeting it to turn into a new millenia, instead of a 626 replacement.
It looks like to me that the 08 Mazda 6 from the rear and side still looks a lot like the current model. Not complaining, just and observation. The front end does look very different, but nothing else. It really doesn't look too much like a redesign. The front end does look like Mazda tried to take styling cues from the RX-8.
looks big in the ass. definitely seems like they are trying to change to market group for the 6, going for those more into the traditional "family sedan". may also have to do with the popularity of the (inferior, imo) 3 amongst younger crowd.
Mazda says the current engines don't "fit" with AWD in the Mazda3 and Mazda6 but that option is being considered for the next generations of each model.
Mazda's Next-Gen Sedans May Get All-Wheel Drive - Motor Trend