Disappointing sales of the compact F-85, along with the introduction of Ford Motor Company's intermediate Fairlane in 1962, prompted GM to enlarge the senior compacts for the 1964 model year.
The new intermediate F-85 now rode a conventional body-on-frame chassis with a perimeter frame. Wheelbase grew to 115 inches (2,900 mm), overall length to 203 inches (5,200 mm), and weight by more than 300 pounds (140 kg). Both the aluminum V8 and the Roto Hydramatic were discontinued in favor of a new cast-iron small-block V8 of 330 cu. in. (5.4L) displacement and an optional two-speed Jetaway automatic transmission with variable-pitch stator. Buick's 225 cu. in. (3.7 L) Oddfire V6 was the standard engine.
The body styles of the previous model returned, and a new Vista Cruiser, a stretched-wheelbase (120"/3048 mm) version of the standard station wagon featuring a raised rear roof with tinted skylights and a fold-down, forward-facing third seat, debuted on February 4, 1964. The 442 model, derived from the BO-9 police package, was also introduced in April 1964(costing $285.14 in 1964), as an answer to the new intermediate muscle car market created by the Pontiac GTO that same year.
Sales increased to 167,002 for 1964, not counting Vista Cruisers.
Source: Wikipedia, 2012