Most manufacturers move until a model is actually on understanding before coming up with special versions of said car. Well, the new GM is apparently not just any car maker.

The long gestation of the U.S.-market Chevrolet Cruze necessitates keeping the public interest up on Chevy's new bread-and-butter midsize sedan. And the company will try to do that with a double-bill of special Cruze versions at this week's New York Auto Show.

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The first, pictured above, is the 2011 Chevrolet Cruze with the optional RS sport appearance package. It'll be acquirable on both LT and LTZ trim levels and, as the study indicates, it is strictly about looks. The RS gets different bumper covers front and rear, rocker moldings, a rear spoiler and fog lamps. Inside, the RS comes with what Chevy is calling "an uplevel instrument cluster," which includes chrome rings in place of standard silver-finish pieces and "opaque cluster bezels," to replace what are apparently transparent cluster bezels on the standard car. We'll let you know what all of that might mean as soon as we find out. Otherwise, the RS is powered by the same 1.4-liter turbocharged four cylinder as other LT and LTZ Cruzes, which puts out an estimated 138 horsepower and 148 lb-ft of torque. (LS models make due with a naturally aspirated 1.8-liter four cylinder).

The other special edition is the Cruze Eco model which is the model that will make good on Chevy's early claim that the Cruze could deliver 40 mpg on the highway. The Eco looks pretty much like all the other Cruzes we've seen, except that it's blue instead of red. That 40 mpg number is for the Eco with the six-speed manual transmission. Numbers for the six-speed automatic-equipped version were not released. The Eco achieves its fuel economy improvement through aerodynamics and low rolling resistance. The lower front grille air shutter closes at higher speeds to reduce drag and opens at lower speeds for engine cooling. Also aiding the aero: The front air barrier is lower, some of the upper grille is blocked off, there's extensive underbody panels and the ride height is lowered. The Eco rides on low-rolling resistance 17-inch Goodyear tires and will get to 60 mph from a stand still in 10 seconds, according to Chevy.