DETROIT – The hybrid variant of the Hyundai Sonata midsize sedan will feature a 6-speed step-gear transmission instead of a continuously variable transmission.

Hyundai Motor America CEO John Krafcik makes the revelation here at the North American International Auto Show.

Though commonly found in hybrid vehicles, “CVTs have nothing to do with hybrids,” Krafcik says, adding the units also are more expensive than step-gear transmissions.

“We removed the torque converter and used the (hybrid system’s) electric motor to provide a lot of the torque-converter functions,” he explains.

The result should be a more affordable hybrid, but the auto maker is mum on pricing. The Sonata HEV is due in fourth quarter.

Developing the system also required some clever maneuvering, “working around Toyota’s very strong patent protection, not just on their hybrid system but every other hybrid system you could possibly think of,” Krafcik says.

It is the same criticism levied against Toyota Motor Corp. by Ford Motor Co. Despite designing its own hybrid system when it launched the Ford Escape Hybrid in 2004, the auto maker licensed the Toyota technology.

Ford has said the move was made to avoid possible patent infringements, an outcome made plausible by Toyota’s numerous patents on technology related to HEV operation.

Toyota is, by a wide margin, the leading seller of HEVs in the U.S.

But the “really cool” feature of the Sonata hybrid is its lithium-polymer battery technology. Most HEVs employ nickel-metal-hydride batteries, but the market is transitioning to lithium-ion. Hyundai’s system represents “third-generation” technology that packs more punch in a smaller package.

“It’s great from a thermal-management standpoint, great in (crashworthiness) – flexible and bendable,” Krafcik says of the Sonata’s battery.

The executive’s remarks come after the auto maker announces it is chasing weight reduction to improve the fuel economy of its vehicles. Hyundai is aiming, by 2015, to reduce by 10% the average weight of its vehicles, says Scott Morgason, HMA’s product planning director.

In addition, Hyundai uses the auto show here to mark the official debut of the ’10 Santa Fe midsize cross/utility vehicle.

Along with the redesigned-for-’11 Sonata, which bows next month, and the redesigned-for-’10 Tucson small CUV, the Santa Fe is among seven new vehicles Hyundai plans to launch in the next 24 months.

The Santa Fe features a pair of new engines: a 2.4L I-4 and a 3.5L V-6. The 175-hp Theta II I-4 is expected to achieve 28 mpg (8.4 L/100 km) on the highway, while the 276-hp Lambda II V-6 is rated at 26 mpg (9.0 L/100 km).

Also on display at the show is the Blue Will, a concept vehicle Krafcik calls a “preview” of a dedicated HEV in Hyundai’s pipeline. He is mum on launch timing.

Meanwhile, Krafcik is coy about Hyundai’s 2010 U.S. sales target. “We do see the industry growing,” he says. “We’d love to get a growing share of a growing market.”

With an 8.3% sales jump over 2008, Hyundai was one of just three auto makers to record sales growth in 2009.