Came across another interesting article about the 2012 Sonata that will help you have a better understanding of the Sonata's powertrain.

More Horsepower meets better Fuel Efficiency
The 2012 Hyundai Sonata’s advanced powertrain delivers the horsepower to drivers. The Sonata features a Theta II Gasoline-Direct-Injected (GDI) 2.4 liter, four-cylinder engine. A greater control over the fuel mixture, at the best possible moment, is facilitated with this more direct path of fuel delivery, resulting in improved fuel efficiency over other engines. A camshaft-driven, high pressure pump injects fuel that runs at pressures up to 2,175 psi. In addition, the Sonata’s direct injection uses a higher than normal 11.3:1 compression ratio, giving Sonata drivers more power. With ‘dished’ design of the pistons increase the combustion efficiency in the cylinder. What does this all add up to?
A best-in-class fuel economy powerplant, with a best-in-class four-cylinder horsepower, and best-in-class torque, for the 2012 Hyundai Sonata!
Featuring a six-speed manual and an automatic transmission with SHIFTRONIC, the Hyundai Sonata delivers a fuel sipping 24 miles per gallon in the city and 35 miles per gallon in the highway fuel economy rating. But that fuel economy doesn’t mean Sonata drivers have to sacrifice power. The Theta II GDI deliver 198 horsepower and 184 lb. ft. of torque.
The Hyundai Sonata Truly Delivers more Under the Hood
Step up to the SE trim level and enjoy the standard dual exhaust, which delivers 200 horsepower and 186 lb. ft. of torque. The 2012 Hyundai Sonata SE’s all-aluminum, 16-valve engine includes Dual Continuously Variable Valve Timing, and a Variable Induction System. There is even a version of this Sonata engine that meets the Partial Zero Emission Vehicle standards, allowing Sonata drivers to not only enjoy a car with some guts under the hood, but an environmentally responsible car as well!
Need more power? Get behind the steering wheel of the 2.0 liter Theta II turbocharged GDI engine, which makes this version of the 2012 Hyundai Sonata the most powerful and a leader in fuel efficiency, in its class. With 274 horsepower and 269 lb. ft. of torque, the Sonata 2.0T will put you back in your seat, and don’t worry about having to stop too often at the gas pump. With an estimated 22 miles per gallon in the city and 33 miles per gallon on the highway, the Hyundai Sonata 2.0T, is as fuel friendly as it is powerful.
Hyundai Sonata Blue Drive Technology
Looking for a more an even more environmentally friendly vehicle? The 2012 Hyundai Sonata’s Blue Drive technology will help you go green. The Sonata Hybrid features a cutting-edge lithium polymer battery pack and engine decoupling that reduces the amount of energy needed to maintain highway speeds. This technology gives the Sonata Hybrid an estimated 40 miles per gallon fuel efficiency on the highway, the best of any mid-size hybrid sedan on the market today!