The parade of updated 2011 Ford Mustangs will march on at the Chicago auto show with the Shelby GT500 receiving a handful of revisions highlighted by a new aluminum block for the 5.4-liter engine. By switching from iron to aluminum, Ford engineers have shaved an impressive 102 pounds from the engine's weight. There's also an upsized intercooler that lowers intake temperatures and a new exhaust that delivers a heartier growl. Those two changes allow output to rise 10 hp to 550 hp while torque remains unchanged at 510 lb-ft. A six-speed manual is still the only transmission.
In all, the 2011 Shelby coupe is 104 pounds lighter than the outgoing 2010 model. Lower weight, a more efficient engine, and improved aerodynamics drive city and highway fuel economy up 1 mpg to 15/23 mpg. That's more significant than you might think, as the 2011 GT500 is no longer hit with the $1300 gas-guzzler tax imposed on every 2010 Shelby.
Shelby convertibles boast a 12-percent improvement in lateral stiffness thanks to strengthening of the existing braces and a new Z-brace connecting the primary and secondary cross members. Special foam in the A-pillar also increases rigidity. Convertible weight is down just 53 pounds compared to last year's Shelby.
Like all other 2011 Mustangs, the GT500 receives electric steering assist in place of the old hydraulic setup. A new glass roof is optional on the coupe while the standard equipment list now includes high-intensity discharge headlamps, fold-down rear headrests, convex side mirror inserts, and the programmable MyKey. The old silver and red hues will be replaced with race red and ingot silver metallic paint.
A new SVT Performance Package allows the GT500 to pull 1.0 g in lateral acceleration and stop 7 percent shorter than a base Shelby, according to Ford. Engineers say those improvements are largely attributed to the stickier Goodyear Eagle F1 SuperCar G:2 tires, but the package includes several other changes. Forged aluminum wheels - 19 inches up front and 20 inches in back - save a total of 15 pounds over the standard Shelby wheels. As the staggered wheel setup increases rear wheel diameter by one inch, there's a 3.73:1 final drive ratio compared to the base Shelby's 3.55:1. A thorough reworking of the suspension has stiffened and shortened the springs and retuned the dampers. A unique rear spoiler increases downforce and uses a small lip at the trailing edge known as a Gurney flap. Front downforce is down 25 percent thanks to better sealing of the cooling ducts and an underbody panel. The few subtle aesthetic changes include thinner stripes over the hood, the removal of the shift-knob stripes, and dampers that have been painted red.
The GT500 changes follow the announcement of new engines for both the Mustang GT and the base pony car. A 305-hp, 3.7-liter V-6 made its debut in November at the Los Angeles auto show. The 412-hp, 5.0-liter V-8 for the Mustang GT was introduced in December ahead of the Detroit auto show.