FOUNTAIN VALLEY, Calif., Jul. 15, 2009 – Gas price spikes over the past year have driven demand for more fuel efficient vehicles. But while customers look to save on fuel, they don’t want to compromise on amenities. Answering the demand, Hyundai added an assembly plant in Alabama building a fuel-sipping 2.4-liter four-cylinder engine to supply its No.1-selling car, the Sonata.