Fourth gneration the 1964 Thunderbird was restyled in favor of a more squared-off, "formal" look. The Thunderbird's sporty image had by that time become only an image. The standard 390-cubic-inch 300 bhp (224 kW) V8 engine needed nearly 11 seconds to push the heavy T-bird to 60 mph (96 km/h), although with enough room a top speed of about 120 mph (200 km/h) was obtainable. The softly sprung suspension allowed considerable body lean, wallow, and float except on smoothly surfaced highways; there was an export suspension package available as special order. Contemporary testers felt that the Buick Riviera and Pontiac Grand Prix were substantially more road-able cars, but the Thunderbird remained the leader of the market segment.
The revised model was initially offered as a hardtop, a convertible, or Landau, with vinyl roof and simulated landau irons. The tonneau cover and wire wheels of the Sports Roadster remained available as a dealer-installed option, although only 50 were sold from the factory. Total 1964 sales were excellent: 92,465, up nearly 50% from the previous year. The 1964 Thunderbird was the only car to have the word 'Thunderbird' on the front hood instead of the image of the Thunderbird.
Several features intended for the new generation were delayed until 1965, when front disc brakes became standard equipment and sequential turn signals were added. The latter feature flashed the individual segments of the broad, horizontal tail lights in sequences from inside to outside to indicate a turn. The delay resulted from legal difficulties with various U.S. state laws on vehicle lighting.