With the war in Europe a reality, the American economic engine began to pick up speed. Production of goods for Europe and increased focus on armaments bumped U.S. auto sales by 30 percent. Chrysler was handicapped by an eight-week strike at the end of 1939 but still gained 42 percent overall. On a sadder note, Walter P. Chrysler died on August 18, 1940.

The 1940 Plymouth sales rose 45.5 percent to 430,208 units and the third-place manufacturer only missed number two Ford by 90,000 units. DeSoto rose 57.2 percent and Chrysler almost 71 percent climbing from 12th to ninth place. Dodge managed a 21 percent increase but slipped from fifth to seventh place.

The 1940 Plymouths resembled the 1939 models, but the frames were significantly redesigned and strengthened. The wheelbase was stretched to 117 inches; front wheels moved back four inches and rear wheels 7.5 inches. That moved the rear seat ahead of the rear axle, and interior space increased by 10 cubic feet. The rear door was no longer cut out for the fender, so access was easier.

Long-wheelbase cars were now a whopping 137 inches between the wheels and a new 3-speed, helical-gear transmission enabled a flat floor on all models. Both 1940 Plymouth P9 Roadking and P10 Deluxe models featured column gear shifting.

The full-length hood stretched to the cowl, front door hinges were concealed, front fenders were flattened and the headlights (now sealed beams) moved outwards. The sedan’s glass area increased 23 percent, with a one-piece rear window. With the Rumble Seat deleted, the Coupe’s passenger compartment was moved forward, permitting a rear seat and increasing trunk space.

Running boards were optional on Deluxe models, and if they were omitted a bright strip was fitted and a rear fender stone shield, to emphasize the difference. Trunk hinges were concealed on all models but the Coupe and Convertible. Broadcloth or mohair was available for closed cars. Leather was optional but it was standard on convertibles. The convertible frame was beefed up which raised the rear floor, so that running boards were recommended but could be deleted.

Plymouth’s reliable 201.3 cubic inch six-cylinder engine was refined with what was called a “superfinish” process and horsepower was raised to 84hp, or 87hp with a high compression head. A new All Weather Air Control System combined heating and defrosting.

The 1940 Plymouth P9 Roadking was built in five body styles and a bare chassis was offered. The 1940 Plymouth P10 Deluxe model offered eight body styles, plus two bare chassis. The PT105 Commercial line continued to offer the Dodge-based ½-ton pickup and the cab and chassis. An ambulance option was available in the Commercial line and could be applied to Roadking and Deluxe models.