Hyundai's strategy to get to 35 mpg is officially called Blue Drive. Blue Drive kicks off in 2009 with new "Blue" editions of the Accent and Elantra that will get better fuel economy at a lower price than current models. The following year, Hyundai's hybrid system will debut in the next generation Sonata along with a lithium-polymer battery. At about the same time a new CUV based on the HED-5 concept will go into production with a new 2.0L turbocharged direct injection engine. Over the following years, downsized turbo DI engines will also appear in other Hyundai models. You can read more about Hyundai's plans over at AutoblogGreen.
[Sources: AutoblogGreen, Hyundai]