General Motors may have left the racing business this year, prompting the 1964 Grand Prix to lose its NASCAR-inspired Super Duty 421 V8s, but the iconic race name stuck with the two-door performance coupe that helped popularize the personal performance car segment along with the Pontiac GTO. Along with the loss of the Super Duty 421s, the 1964 Grand Prix got a few horsepower boosts and downgrades in its other V8s. The 389 2-barrel still hit 230-hp, and the 4-barrel got 303 with the Hydramatic auto tran, but when coupled with a manual, it now reached 306-hp. The 389 TriPower went from 318 to 330-hp, while the 421 4-barrel slipped a bit down to 320-hp. The High Output 421 remained virtually the same at either 350 or 370-hp. All came with either a 3 or 4-speed manual or Hydramatic auto tran. On the outside, the 1964 Grand Prix still sported the unique concave rear window and straightforward Coke bottle body. The split grille was altered again, with horizontal slats. The stacked headlights remained, but the turn signals became more ovoid and lost the chrome strips. The cabin got a few color and material updates, but nothing changed in terms of the nice standard features that complemented the exciting driving experience in the 1964 Grand Prix.