ATS spied with some camo removed

As you can see in this image from the Detroit News, we can start to make out some of the real sheetmetal of the ATS, including character line swooping up the door skin and some of the actual shape of the rear window and C-pillar. As the article notes, the trunk looks to be super short, taking some fastback-esque styling queues from the CTS coupe. Source: Detroit News