This is the Cadillac Elmiraj concept. It's the 500 horsepower, 21st Century American luxury coupe you've been dreaming of.
The Elmiraj is a counterpoint to the Ciel, the last concept car Cadillac brought to Pebble Beach. The Ciel was a boulevardier, a luxury convertible in the mold of the art deco 1930s.
The Elmiraj is an altogether more 1950s machine. Look at the mesh grill in front of the 4.5 liter, 500 horsepower, twin turbo V8. The 'V' badge between the two tailpipes melded into the fenders. It's like you're looking at a modern interpretation of an early Eldorado.
The styling is very restrained, but it sufficiently conspires to make your car look like a turd next to it, which is a great measure of Cadillac-ness.
Cadillac says that the Elmiraj is based on "an ongoing Cadillac vehicle development project slated for future production." Maybe this is the coupe concept for the S Class-competing sedan we've been hearing about?
(Hat tip to Juan Barnett!)