1970
The Tempest line received another facelift for the 1970 model year. Hidden headlights were deleted in favor of four exposed round headlamps outboard of narrower grille openings. The nose retained the protruding vertical prow theme, although it was less prominent. While the standard Tempest and LeMans had chrome grilles, the GTO retained the Endura urethane cover around the headlamps and grille.
The suspension was upgraded with the addition of a rear anti-roll bar, essentially the same bar as used on the Oldsmobile 442 and Buick Gran Sport. The front anti-roll bar was slightly stiffer. The result was a useful reduction in body lean in turns and a modest reduction of understeer.
Another handling-related improvement was optional variable-ratio power steering. Rather than a fixed ratio of 17.5:1, requiring four turns lock-to-lock, the new system varied its ratio from 14.6:1 to 18.9:1, needing 3.5 turns lock-to-lock. Turning diameter was reduced from 40.9 feet (12.5 m) to 37.4 feet (11.4 m).
The base engine was unchanged for 1970, but the low-compression economy engine was deleted and the Ram Air III and Ram Air IV remained available, although the latter was now a special-order option.
A new option was Pontiac's 455 engine, available now that GM had rescinded its earlier ban on intermediates with engines larger than 400. The 455, a long-stroke engine taken from the full-size Pontiac Bonneville line, was only moderately stronger than the base 400 and actually less powerful than the Ram Air III. The 455 was rated at 360 hp (268 kW) @ 4,300 rpm. Its advantage was torque: 500 ft-lbf (677 N-m) @ 2,700 rpm. A functional Ram Air scoop was available, but even so equipped, a stock 455 was less powerful than the Ram Air III. Car and Driver tested a heavily optioned 455, with a four-speed transmission and 3.31 axle and recorded a quarter mile time of 15.0 seconds with a trap speed of 96.5 mph (155.3 km/h). Car Life's Turbo-Hydramatic 455, with a 3.35 rear differential, clocked 14.76 seconds at 95.94 mph (154.40 km/h), with identical 6.6 second 0-60 mph acceleration. Both were about 3 mph (5 km/h) slower than a Ram Air III 400 four-speed, although considerably less temperamental: the Ram Air engine idled roughly and was difficult to drive at low speeds. The smaller displacement engine recorded less than 9 miles per gallon of gasoline (26.1 L/100 km), compared to 10 to 11 miles per gallon (23.5 to 21.4 L/100 km) for the 455.
A new and short-lived option for 1970 was the Vacuum Operated Exhaust (VOE), which was vacuum actuated via an underdash lever marked "EXHAUST." The VOE was designed to reduce exhaust backpressure to increase horsepower and performance, but it also substantially increased exhaust noise. The VOE option was offered from November 1969 to January 1970. Pontiac management was ordered to cancel the VOE option by GM's upper management following a TV commercial for the GTO that aired during Super Bowl IV on CBS January 11, 1970. In that commercial, entitled "The Humbler," which was broadcast only that one time, a young man pulled up in a new GTO to a drive-in restaurant with dramatic music and exhaust noise in the background, pulling the "EXHAUST" button to activate the VOE and then left the drive-in to do some street racing. That particular commercial was also cancelled by order of GM management. Approximately 230 1970 GTOs were factory built with this rare option. A few mufflers have been "Hand-made" for the remaining cars; this occurred in 2006 and 2007.
The Judge remained available as an option on GTOs. The Judge came standard with the Ram Air III, while the Ram Air IV was optional. Though the 455 in³ was available as an option on the standard GTO throughout the entire model year, the 455 was not offered on The Judge until late in the year. "Orbit Orange" became the new standard color for the '70 Judge, but any GTO color was available on The Judge. Striping was relocated to the upper wheelwell brows.
An Orbit Orange 1970 GTO Judge with the 455 engine and Turbo Hydra-Matic transmission was one of the featured cars in the movie "Two-Lane Blacktop", which depicted a cross-country race between the new GTO and a 1955 Chevrolet Bel Air.
The new styling did little to help declining sales, which were now being hit by sagging buyer interest in all muscle cars and by the punitive surcharges levied by automobile insurance companies, which sometimes resulted in insurance payments higher than car payments for some drivers. Sales were down to 40,149, of which 3,797 were The Judge. The GTO remained the third best-selling intermediate muscle car, outsold by the Chevrolet Chevelle SS 396/454 and Plymouth Road Runner.
1971
The 1971 GTO had another modest facelift, this time with wire-mesh grilles, horizontal bumper bars on either side of the grille opening, more closely spaced headlamps, and a new hood with the dual scoops relocated to the leading edge, not far above the grille. Overall length grew slightly to 203.3 inches (516 cm).
A new corporate edict, aimed at preparing GM for no-lead gasoline, forced a cross-the-board reduction in compression ratios. The Ram Air engines did not return for 1971. The standard GTO engine was still the 400 in³ V8, but now with 8.2:1 compression. Power was rated at 300 hp (223 kW) @ 4,800 rpm and torque at 400 ft-lbf (542 N-m) @ 3,600 rpm. An engine option was the 455 in³ V8 with four-barrel carburetor, 8.4 to 1 compression ratio and 325 hp (242 kW), only available with the automatic transmission. The top GTO engine for 1971 was the new 455 HO with 8.4 compression, rated at 335 hp @ 4,800 rpm and 480 ft-lbf (650 N-m) @ 3,600 rpm.
Motor Trend tested a 1971 GTO with the 455, four-speed transmission, and 3.90 axle, and obtained a 0-60 mph time of 6.1 seconds and a quarter mile acceleration of 13.4 seconds at 102 mph (164 km/h).
The Judge returned for a final year, now with the 455 HO as standard equipment. Only 374 were sold before The Judge was discontinued in February 1971, including 17 convertibles—today the rarest of all GTOs.
Only 10,532 GTOs were sold in 1971.
1972
In 1972, the GTO reverted from a separate model line to a US$353.88 option package for the LeMans and LeMans Sport coupes. On the base LeMans line, the GTO package could be had with either the low-priced pillared coupe or hardtop coupe. Both models came standard with cloth and vinyl or all-vinyl bench seats and rubber floor mats on the pillared coupe and carpeting on the hardtop, creating a lower-priced GTO. The LeMans Sport, offered only as a hardtop coupe, came with Strato bucket seats upholstered in vinyl, along with carpeting on floor and lower door panels, vinyl door-pull straps, custom pedal trim and cushioned steering wheel, much like GTOs of previous years. Other optional equipment was similar to 1971 and earlier models. Planned for 1972 as a GTO option was the ducktail rear spoiler from the Pontiac Firebird, but after a few cars were built with that option, it was cancelled. Rally II and honeycomb wheels were optional on all GTOs, with the honeycombs now featuring red Pontiac arrowhead emblems on the center caps, while the Rally IIs continued with the same caps as before, with the letters "PMD" (for Pontiac Motor Division).
Horsepower, now rated in SAE net terms, was down further, to 250 hp (186 kW) @ 4,400 rpm and 325 ft-lbf (440 N-m) @ 3,200 rpm torque for the base 400 engine. The optional 455 had the same rated horsepower (although at a peak of 3,600 rpm), but substantially more torque. Most of the drop was attributable to the new rating system (which now reflected an engine in as-installed condition with mufflers, accessories, and standard intake). The engines were relatively little changed from 1971.
A very rare option was the 455 HO engine, essentially similar to that used in the Trans Am. It was rated at 300 hp (224 kW) @ 4,000 rpm and 415 ft-lbf (562 N-m) @ 3,200 rpm, also in the new SAE net figures. Despite its modest 8.4:1 compression, it was as strong as many earlier engines with higher gross power ratings; yet like all other 1972-model engines, it could perform on low-octane regular leaded, low-lead or unleaded gasoline's. Only 646 cars with this engine were sold.
Sales plummeted by 45%, to 5,811. (Some sources discount the single convertible and the three anomalous wagons, listing the total as 5,807.) Although Pontiac did not offer a production GTO convertible in 1972, a buyer could order a LeMans Sport convertible with either of the three GTO engines and other sporty/performance options to create a GTO in all but name. Even the GTO's Endura bumper was offered as an option on LeMans/Sport models, with "PONTIAC" spelled out on the driver's side grille rather than "GTO."