What is the name of the first car with a V16 engine?

The Cadillac V-16 was the first production car with a V16 engine.

Cadillac introduced the V-16 in January 1930 as its new top-level luxury model. Its 452-cubic-inch engine used a 45-degree cylinder angle, overhead valves, and sixteen cylinders arranged in two banks. The engine produced about 165 horsepower, an extraordinary figure for the period, while also delivering exceptionally smooth operation.

The car was developed under Cadillac general manager Lawrence Fisher, with engineer Owen Nacker leading the engine design. Each chassis could be custom-finished with bodywork from coachbuilders, including Fleetwood, and buyers could choose from numerous body styles and colors. That made the V-16 both a technical showcase and a highly personalized prestige automobile.

Marmon had actually begun developing its own V16 engine earlier, in 1927, but its Marmon Sixteen was not released until 1931. That timing explains the frequent mix-up: Marmon may have started development first, but Cadillac was first to put a V16 into a production automobile. Cadillac built 4,076 V-16s during the model’s 1930–1940 run.