The rear-drive sedan, which GM plans to launch in the second half of next year, is among four world debuts of production or concept vehicles that GM plans for its hometown show.
Barra didn't disclose the other three during her remarks here at an Automotive Press Association event.
"The ATS is really a crucial part of our Cadillac strategy," Barra said, noting that it is one of the biggest segments in the global luxury industry, "both from a volume and an importance perspective."
GM is aiming the ATS at the BMW 3 series and other entrenched entries in the compact luxury market such as the Mercedes C class and the Audi A4.
The ATS will be built at a GM plant in Lansing, Mich., alongside the CTS coupe, sedan and wagon.