The Tempest line, including the GTO, was restyled for the 1965 model year, adding 3.1 inches to the overall length while retaining the same wheelbase and interior dimensions. It sported Pontiac's characteristic vertically stacked quad headlights. Overall weight increased about 100 pounds. Brake lining area increased nearly 15%. The dashboard design was improved, and an optional rally gauge cluster for $86.08 added a more legible tachometer and oil pressure gauge.
The 389 engine had revised cylinder heads with re-cored intake passages, improving breathing. Rated power increased to 335 hp at 5,000 rpm for the base 4—barrel engine; the Tri-Power was rated 360 hp at 5,200 rpm. The Tri-Power engine had slightly less torque than the base engine, 424 lb·ft at 3,600 rpm versus 431 lb·ft at 3,200 rpm. Transmission and axle ratio choices remained the same.
The restyled GTO had a new simulated hood scoop. A rare, dealer-installed option was a metal underhood pan and gaskets that allowed the scoop to be opened, transforming a cosmetic device into a functional cold air intake. The scoop was low enough that its effectiveness was questionable (it was unlikely to pick up anything but boundary layer air), but it at least admitted cooler, denser air, and allowed more of the engine's formidable roar to escape.
Car Life tested a 1965 GTO with Tri-Power and what they considered the most desirable options (close-ratio four-speed manual transmission, power steering, metallic brakes, rally wheels, 4.11 limited-slip differential, and Rally Gauge Cluster), with a total sticker price of $3,643.79. With two testers and equipment aboard, they recorded 0-60 miles per hour in 5.8 seconds, the standing quarter mile in 14.5 seconds with a trap speed of 100 miles per hour, and an observed top speed of 114 miles per hour at the engine's 6,000 rpm redline. Even Motor Trend's four-barrel test car, a heavier convertible handicapped by the two-speed automatic transmission and the lack of a limited slip differential, ran 0-60 mph in 7 seconds and through the quarter mile in 16.1 seconds at 89 miles per hour.
Major criticisms of the GTO continued to center on its slow steering (ratio of 17.5:1, four turns lock-to-lock) and mediocre brakes. Car Life was satisfied with the metallic brakes on its GTO, but Motor Trend and Road Test found the standard drums with organic linings to be alarmingly inadequate in high-speed driving.
Sales of the GTO, abetted by a formidable marketing and promotional campaign that included songs and various merchandise, more than doubled to 75,342. It was already spawning many imitators, both within other GM divisions and its competitors.
