This was America’s fastest and most powerful production car on the road in 1956. The 1956 300B was fairly similar externally to the original 1955, distinguished by a new tailfin treatment, but with larger engines, and a choice of two versions of the 354 cu in (5.8 L) Hemi V8 producing either 340 or 355 hp, with a 10:1 compression ratio used to achieve the higher horsepower rating. A companion of this generation was introduced as the DeSoto Adventurer and the Dodge D-500 that were less luxurious, while still sharing much of the mechanicals, giving DeSoto and Dodge a performance enhanced model, while the 354 CID engine was exclusive to the 300, New Yorker and Imperials. The TorqueFlite transmission controls were to the left of the steering wheel and a total of 1,102 were sold. Performance was better than the previous year’s by its top speed at almost 140 mph (225 km/h) at the Daytona Flying Mile. Front leg room was 44.6 inches.^[6] New was the Highway Hi-Fi phonograph player. This was the last year that coil springs were used for the front suspension.^[6][5]

With the optional 10:1 compression ratio, brake horsepower became 355 hp from the same 354 cu in (5.8 L) engine, and the 300B became the first American car to produce 1 horsepower per cubic inch, besting Chevrolet with their fuel-injected 283 cu in (4.6 L) by one year. Colors were updated to Regimental Red, Cloud White and Raven Black while the tan leather interior remained.

NASCAR team owner Carl Kiekhaefer‘s raced the 300B, among other cars, and won 22 out of 41 races, including 16 races consecutively; one of his racers was famous racer Buck Baker, who drove 300B’s. Kiekhaefer would purchase cars from Chrysler and modify a few appearance features but essentially raced the cars as they were, with leather interior and other standard features, on the racetrack.^[5] NASCAR Hall of Famer Vicki Wood also set the women’s speed record in a 300 during ’55 and ’56. The listed retail price, before options was just north of $4,300.