Muscular new engines infuse Mustang with tire-smoking performance. The 4.6-liter all-aluminum V-8 has three-valve heads and cranks out 300 horsepower. Because it has an aluminum block, it weighs 75 pounds less than a comparable cast-iron design while delivering 40 more horsepower than the 2004 engine. That’s more than 50 percent more power than the small-block 289-cubic-inch V-8 found in the classic 1964 model. Motor Trend ran a 2005 Mustang GT 5-speed from 0 to 60 in 5.1 seconds and ran the quarter mile in 13.5 seconds at 103 mph in the January 2005 issue. The Mustang GT comes standard with a rear spoiler, but a spoiler delete option is available. 17" wheels are standard.

A TREMEC five-speed manual transmission is standard, but for the first time, a five-speed automatic transmission is available.

GT Deluxe: 4.6-liter 3-valve V-8 engine, ABS with traction control, stainless steel dual exhaust, front fog lamps in grille, complex reflector halogen headlamps with integral turn signals, rear spoiler, performance tires with 17-inch painted cast aluminum wheels, AM/FM stereo with single CD, cloth sport bucket seats and leather-wrapped tilt steering wheel.

GT Premium adds: Shaker 500 Audio system with six-disc CD player and Aberdeen leather-trimmed embossed sport bucket seats.

The 2005 Mustang GT was selected to pace the NASCAR Nextel Cup Banquet 400 and Ford 400 in the 2004 season.

Invariably some changes are made between the time preproduction cars are made and when the full production run is started. The 2005 Mustang was no exception. The major differences are that on the preproduction cars, the vertical bars in the lower front valence were painted to match the body, the GT had a "Powered By Ford" engine cover, the 5-speed manual shifter was polished aluminum, and the pony medallion on the steering wheel was surrounded in silver on cars equipped with the Interior Upgrade Package. The 18" wheels found on the preproduction show cars have been delayed until model year 2006.