The PV444 was Volvo's first uni-body car. It was also the first Volvo in almost 20 years to come with a 4-cylinder engine. The first PV444s were powered by a 40 PS 1.4 L inline-four engine designated the B4B, with three main bearings, overhead valves, and a single downdraft carburettor. The power of this engine increased to 44 PS (32 kW) in October 1950, and to 51 PS (38 kW) in October 1955. US models, beginning to appear in the US in early 1956, received an uprated version called the B14A which was given twin side-draught 1½ in SU carburettors for a total of 70 hp. Most early US sales were limited to Texas and southern California. American customers also had the option of European delivery, in which case they could also get a cheaper model with the basic B4B engine.
By the 1957 model engine displacement was increased to 1.6 L and both single downdraft- B16A and twin side-draught-carburetted B16B versions were offered. Fuel economy was quite above average and performance particularly with the twin carburetor configuration was good. The combination of performance and durability won over many two-seat sports car drivers, allowing them a pleasurable drive in the entire family's company if desired.