Like all automakers, Nash-Kelvinator suspended production of its 1942 model year cars when America entered the Second World War, and when production restarted in late 1945, the 1946 model year cars were an identical continuation series of the prewar designs. With the American people hungry for new cars after three years of no production whatsoever and the economic distress of the Great Depression before that, Nash rushed to take part in the booming postwar automobile market.

In the case of the Nash Ambassador, the prewar design that carried over was a full-size, body-on-frame car with an unusual 234 cubic inch overhead valve inline six-cylinder engine rated at 112 hp. The Ambassador engine offered state of the art features such as aluminum alloy pistons, automatic spark control, and a balanced crank with a vibration dampener. The only transmission offered was a three-speed manual with optional overdrive. The Ambassador was also known for its 20 gallon fuel tank that allowed drivers to go 600 miles between fill-ups.

The Ambassador was designed to compete with Cadillac and Lincoln models at the high end of the market, but Nash dropped its prewar straight-eight engines in favor of the more economical six-cylinder. Even so, all the amenities available in this era were present in the Ambassador line. Air conditioning was available, along with foam seats, a radio and turn signal lights. Body styles included a four-door trunk sedan, two-door Brougham sedan, four-door Suburban, and the four-door fastback sedan known as a Slipstream. Four-door models featured suicide rear doors.

1947 Ambassadors were unchanged from 1946, but the car was honored in this year as the official pace car of the Indianapolis 500. 1948 saw some upgrades to trim, and the addition of a two-door convertible to the line.

Fastback sedans and trunk sedans were by far the most popular, amounting to well over 75 percent of production. Total production of the Ambassador line was about 40,000 cars per year in 1946 and 1947, and about 50,000 cars in 1948. In 1946, that production broke down to 7,300 four-door trunk sedans, 8,500 two-door brougham sedans, and 42,300 four-door fastback sedans. In 1947, Ambassador production broke down to 15,927 four-door trunk sedans, 8,673 two-door Brougham sedans, 14,505 four-door Slipstream fastback sedans, and 595 of the new wood-bodied Suburban four-door fastback sedans.

For the final year of this era, production included 18,350 four-door trunk sedans, 8,150 two-door Brougham sedans, 18,910 four-door Slipstream fastback sedans, 130 four-door Suburbans, and a new two-door convertible model with 1,000 units produced. In 1948, there was an ugraded “Custom” trim line that accounted for about 10,000 cars in all bodies except Suburban. All convertibles were part of the Custom trim line.

The rarest of the Ambassadors in this era are the 1,000 wood-bodied Suburban sedans from 1946-1948, and the 1,000 convertibles made in the 1948 model year. This was the last period for traditional body-on-frame cars from Nash. Following the 1948 model year, Nash moved forward with the space age Airflyte models that used a unibody chassis.