Not to be outdone, Cadillac began work on an engine to top all others, a V-16, and a V-12 derived from it to place the company on equal footing with the few manufacturers producing one.

Larry Fisher, Cadillac General Manager, leaked to the press information about the V-12, hoping to keep the V-16 a secret.

The Cadillac V-12 might have been lower in prestige than the Cadillac V-16, but it joined a select group of 1930s cars with multicylinder engines, namely those manufactured by Auburn, Franklin, Hispano-Suiza, Horch, Lagonda, Maybach, Packard, Pierce-Arrow, Rolls-Royce, Tatra, Voisin, Walter, Marmon and Lincoln.

Mechanical changes included a stiffer frame, and a Cuno self-cleaning oil filter mounted at the right hand side of the clutch housing.

The radiator grill slanted rearward with a central bar and five horizontal sections, the windshield sloped even more rearward, headlights were enclosed in new teardrop housings mounted on streamlined supports, the horns joined the radiator cap under the hood, the spare tire was concealed under a new beaver tail deck on most models and the whole car sat approximately 2 inches (51 mm) lower.

Significant mechanical advancements included dual X-frame chassis construction, "Knee-Action" front coil spring suspension that greatly reduced unsprung weight and Hotchkiss steering.

[1] As part of the General Motors V-Future program, Cadillac had an overhead cam V-12 slated for production in the late 1960s.

[5] The program led to a fiberglass mockup of a V-12 powered Eldorado coupe that remained hidden from public view until an article appeared in Special Interest Autos in 1984.

[11] The Cadillac Sixteen concept utilized an all-aluminium pushrod V-16 engine based on the same architecture as GM's then-current small-block V-8 developments.