'65-'66 Shelby GT350When the Shelby GT350 hit the scene in 1965, the enthusiast press jumped all over it. Powered by a 306hp Cobra version of the 289 High Performance and equipped with suspension modifications for improved handling, the GT350 was more race car than road car, especially in 1965, when it had side exhaust and no rear seat.
By 1966, the GT350 was a bit more refined, but it was also available with an optional Paxton supercharger, a package that boosted the Shelby's performance to 14-flat, as evidenced by the test reports in both Motor Trend and Car Life in the summer of 1966.
Most naturally aspirated GT350s performed in the high-14, low-15-second range, including a Hertz rental car version with the automatic transmission. Oddly, the '65 tested by Motor Trend was a full second slower than the one tested by Car Life.
| '66 GT350S | 14.0/102 | auto | 3.89 | Motor Trend, Aug. 1966 |
| '66 GT350S | 14.0/92 | auto | 3.89 | Car Life, July 1966 |
| '65 GT350 | 14.7/90 | 4-spd. | 3.89 | Car Life, June 1965 |
| '65 GT350 | 14.9/95 | 4-spd. | 3.89 | Car & Driver, May 1965 |
| '66 GT350H | 15.2/93 | auto | 3.89 | Car & Driver, May 1966 |
| '66 GT350 | 15.6/94 | 4-spd. | 3.89 | Motor Trend, Aug. 1966 |
| '65 GT350 | 15.7/91 | 4-spd. | 3.89 | Motor Trend, May 1965 |
'67-'68 390Car Life called it the "Super Double Deluxeburger Mustang" because Ford decided to add the 390 big-block to the Mustang's engine lineup. With 320 hp and 427 lb-ft of torque, the pony-sized Mustang finally had some beef to compete against big-block GTOs and Barracudas, not to mention the new 396 Camaro.
In stock form, the 390 Mustang was a low-to-mid-15-second performer, as evidenced by most of the road tests. Car & Driver reported a 14.8-second e.t. and even complained that the car was not in optimum tune, but failed to provide the transmission type or how they managed to obtain a quicker time than anyone else. Hi-Performance Cars magazine, however, explained that it took a set of slicks and traction bars to register their 14.95-second e.t., stating, "Normally, the 390 engine cannot be considered hot by today's standards. However, when packed into a light Mustang, you have a pretty impressive machine."