The ATS' narrower headlights represent the closest interpretation yet of the slit-like lamps on Cadillac's Ciel and Converj concepts shown in 2011 and 2009, respectively. The protruding nose with an offset center bumper inlet recalls GM's Buick Regal, though the cars ride separate platforms. The Cadillac's short tail holds two inboard tailpipes, and it has a shoulder line that materializes under the C-pillar, winds around the trunk and disappears a few inches from Cadillac's deck logo. Seventeen-inch alloy wheels are standard, with 18s optional.

The ATS is 8.5 inches shorter than the CTS; it's also 1.4 inches narrower and 2.1 inches shorter in height. The footprint mirrors the 3 Series, while the A4 and TSX are a bit larger. The shrink-wrapped package affects trunk volume, which measures a scant 10.2 cubic feet.