Just as Mustangs of years past, the 2011 model is available as a 4-passenger coupe or convertible, with a choice of a V6 or V8 engine. The base model receives an all-new 3.7L Duratec V6 making 305 horsepower and 280 lb-ft of torque in place of last year's 210-horsepower, 4.0L V6. The Mustang GT models see the return of a 5.0L V8, a displacement all too familiar to Mustang fans. It has been completely redesigned however, and features 32 valves, variable camshaft timing and an output of 412 horsepower. Both models now offer either a standard 6-speed manual or a 6-speed automatic transmission. Joining the lineup this year is a repowered version of the Shelby GT500, a high-performance variant of the Mustang that will now offer 550 horsepower from its new all-aluminum supercharged 5.4L V8 engine. As before, it will only be available with a heavy-duty Tremec 6-speed manual transmission--and as before the GT500 is distinguished by its twin racing stripes running the length of the vehicle. Tuned suspension, improved steering feel and, for coupes, high-speed-rated Goodyear Eagle F1 Supercar tires are also standard, helping to get more out of the tremendous engine. The sheetmetal of all the Mustang models returns unchanged from the 2010 model, although new side mirrors with an integrated spotter mirror have been added, aiding in rear visibility and cutting down on blind spots. The overall interior packaging of the Mustang changed little, which means that quarters are tight, but front occupants will fit comfortably into supportive bucket seats while smaller adults or children will fit acceptably in the back seat. A retuned suspension in the Mustang brings a greatly improved ride while also improving handling, and updated sound insulation assures a quieter cabin. A 160-mph speedometer and an 8,000 rpm tachometer are now standard, and deep-dish gauges with bright chrome trim rings return, as does 2010's 3-spoke steering wheel that includes audio and cruise controls. The latest safety features are also included in this affordable sport car, with electronic stability control, anti-lock brakes and seat-mounted side airbags standard across the Mustang line. Both the coupe and convertible are offered in base, Premium, GT and GT Premium models. GT trims add the V8 engine, larger wheels and tires, fog lamps and a stainless-steel exhaust. In both versions, the Premium trim adds a host of interior comforts and conveniences, such as leather upholstery, aluminum accents, a My Color interior ambient lighting system, Shaker 500 premium audio, Sirius Satellite Radio and Ford's Sync interface, which allows hands-free calling through Bluetooth cellphones and control of audio devices. Returning for 2011 is the GT/CS (or California Special), which is only available on the GT Premium and includes a chrome billet grille, side stripes, unique lower fascia and rear diffuser, special 19-inch wheels and a host of interior upgrades. A Mustang Club of America Special Edition is also available, which only comes on the V6 Premium and features special MCA badging, side stripes, 18-inch wheels, and Pony logo floor mats. Highlights of the option list include dual-zone climate control, a voice-activated navigation system, remote start, a rear video camera, HID headlamps, HD radio and a large glass roof.