Here's my crack at the whole RWD DTS schtick.
It's based off of the nonexistent Sigma II platform with a long wheelbase. Mercedes-Benz and Lexus have comfort, Audi and BMW have performance...the Cadillac D-Line effectively splits the difference.
Standard engine in the DTS is a new twin-turbocharged (two smalls as opposed to one big) 3.6L DIV6, good for roughly 375-415hp. An available DTS-H gains a hybrid-electric powertrain, with the 3.6L DIV6 as the gasoline motor, good for an equivalent of 290-310hp.
Here we go...
Oh, by the way, the side vent is fully functional.