[7] The objective of George W. Mason as president of the newly merged Nash-Kelvinator company was to transform Nash's automobile image in the marketplace.

[6] Nash's body design innovation meant new tooling for the Kenosha factory to build the cars, but also required new techniques for collision repairs.

[7] The "600" designation for this Nash reinforced the automaker's claim for the car's ability to travel over 500 miles (805 km) on one tank of gasoline.

Four body versions were available: a four-door Slipstream (fastback) sedan with no protruding lights, running boards, or door hinges; a four-door Sedan with built-in trunk (now called notchback style), a Coupe Brougham with full-width front and rear seats, and a Business Coupe featuring a roomy rear deck cargo compartment.

[3] Similar to the Mobilgas Economy Run, a 1941 event sponsored jointly by the American Automobile Association (AAA) and Gilmore Oil, a California-based petroleum company, saw the new Nash 600 deliver 25.81 mpg‑US (9.11 L/100 km; 31.00 mpg‑imp) on regular roads and be proclaimed a "Best in Class" winner.

[20] This was the lowest-priced model with minimal features, lacking a back seat (to have room for samples) as well as no chrome trim, ornamentation, or comfort items such as a sun visor and door armrest.

"The envelope shape was the most streamlined form on the road, a large step ahead of the vaguely similar Packard luxury models produced from 1948 through 1950.

[23] The 600 became the economical series competing with Chevrolet, Ford, and Plymouth; while the Ambassador became the premium models and up against brands as Buick, Oldsmobile, Mercury, Chrysler, DeSoto, and Hudson.

Optional was a new "Twin Bed" that transformed the car's interior into a double sleeping area, making it perfect for camping or impromptu overnight use.

A long, upholstered horizontal surface was formed by dropping the two front passenger seatbacks down to meet with the bottom of the rear bench seat.

Additional comfort was available by Nash dealer accessories, including form-fitting mattresses that filled gaps between the seats and snap-in screens for the door windows, in order to provide ventilation and keep out insects.

The 1949 Nash 600 series were built on a 112-inch (2,845 mm) wheelbase and carried over the previous 172.6 cu in (2.8 L) I6 engine, selling at lower prices than the Nash Ambassador series that now rode on a larger 121-inch (3,073 mm) wheelbase and boasted a standard 234.8 cu in (3.8 L) overhead-valve I6 engine with a durable seven-main bearing design.