Hyundai\'s first U.S.-bound hybrid is due to be released in late 2010, and the next-generation Sonata-based hybrid has its aim set on the stalwarts of the midsize sedan segment. As we can see from this series of spy shots, testing is well underway, with a heavily camouflaged 2011 Sonata Hybrid out and about with hybrid versions of the Ford Fusion, Toyota Camry and Nissan Altima in tow.

Hyundai has taken a slightly different approach to energy storage, using flat lithium polymer battery packs holding 5.3 Ah of capacity at 270 volts in lieu of nickel metal hydride or lithium ion technology. Expect the hybrid bits to add 30kW of power to Hyundai\'s 2.4-liter Theta II four cylinder powerplant mated up with a six-speed automatic transmission. A quick glance underhood shows the telltale bright orange wiring normally associated with hybrid automobiles.

A closer look at the spy photos shows that Hyundai will apply the popular four-door coupe trend to its next Sonata. We also clearly note radically sweeping headlamps that stretch all the way past the front wheel arches, a rising bodyside ridge and a vaguely Genesis-esque front grille treatment. Expect all of these styling elements on both the standard 2011 Sonata and its accompanying hybrid sibling.