Who would have imagined a few years back that there would be so much interest in a new generation of the Hyundai Sonata that it would be totally justified for us to stay up until the early morning hours to write a post on the car… But times change, GM went in and out of bankruptcy protection, the Fiat Group acquired Chrysler and surprise, surprise, Hyundai overtook the Ford Group in the first half of the year to become the world’s fourth largest automaker. So there you have it. But let’s wind back back to the Sonata. After more leaks than a New Orleans levy, the Korean maker formally introduced the four-door sedan in its home market today.

“The Sonata will set a new standard for world class mid-size sedans with state-of-the-art technology, superior build quality and emotional design,” said Euisun Chung, Hyundai’s Vice Chairman at the launching ceremony for the car in Seoul. “The new Sonata will raise Hyundai’s brand values.”

It might not be an Alfa Romeo, but compared to its dull and unimaginative predecessors, we’d say that the sixth-generation Sonata makes a huge step (call that a leap) forward in terms of design. Some will even claim that it clearly adopts styling cues from the so-called four-door coupe segment such as the swooping roofline and the stubby rear end, and they’re probably right.

The Sonata also boasts a fresh interior with a contemporary styling that’s in line with the Korean firm’s latest products such as the new Tucson / ix35 SUV that was revealed at this week’s Frankfurt Motor Show.

Size-wise the Sonata is 4,820mm long, 1,835mm wide and 1,470mm tall with a wheelbase of 2,795mm making it a little longer and wider but slightly lower than the outgoing model.

The Sonata, which may be sold under a different name in some regions (e.g. i40 in Europe), will be offered at launch in its home market with a 2.0-liter Theta II MPi gasoline engine with 165HP and an LPG version that makes 144HP. Both engines are paired to a new six-speed automatic transmission.

Hyundai said that it plans to add 2.4 liter Theta II GDI gasoline engine to the range in January next year. This engine will be offered as standard on the U.S. market model.

All versions of the Sonata will be equipped with a standard Vehicle Dynamic Control with Hill-start Assist Control and Brake Assist System functions. Other highlights include an available three-piece panoramic sunroof and a new Parking Guide System (PGS) that allows the driver to avoid obstacles during parallel parking or when driving in reverse – or so the company claims.

Hyundai said that it began developing the new Sonata in 2005 under the codename YF with the project costing a total of 450 billion won (US$ 372 million) to go from concept to production.

The company plans to sell 60,000 units of the new Sonata in Korea this year. With the addition of production in its U.S. plant in Alabama plant in early 2010 and in China the following year, Hyundai expects that number to raise to 450,000 units annually worldwide from 2011.

In South Korea, the new Sonata’s prices range from 21.3 million Won to 25.95 million Won (US$17,600 to US$21,450).

Update: Click here to check out the video story on the new Hyundai Sonata