Instead of gasoline/electric, the Avante Hybrid will feature an LPG/electric setup in order to take advantage of the low price of Liquid Petroleum Gas in Korea (it's half the cost of the dino juice), and the fact that there's a working LPG infrastructure there already. They'll need government help to loosen up some regulations, because right now, LPG is reserved for rental cars and handicapped transport. The fact that Hyundai's moving forward with the plan is a pretty clear indicator that it expects the rules will be modified to allow regular citizens to purchase LPG-powered cars.
When combined with the hybrid system, the Avante is expected to pull down fuel economy in the neighborhood of 47 mpg. A gasoline/electric hybrid is also reportedly planned for 2010. Maybe we'll get that one.