Autoblog is posting these spy shots of a modified CTS sedan at the test track.
By noting the re-positioned fuel filler door as well as the much shorter wheelbase, we might assume that this is a mule for Alpha (i.e. the ATS).
If they are at this phase of development, however, this suggests both that the earlier spy shots of a purported ATS testing in production sheet metal must have been faked. This also means that either they are being very protective of the final look, or ATS is further away then we might have hoped.
Or…we could be looking at some other development of a rear drive car where they’ve chosen to use a CTS body shell to throw us all off (could be the next Camaro chassis under there – which is also Alpha but a year or two further out than the ATS).