 The Hyundai Elantra LPI Hybrid was unveiled at the 2009 Seoul Motor Show, and sales began in the South Korean domestic market in July 2009.The Elantra LPI (Liquefied Petroleum Injected) is the world's first hybrid vehicle to be powered by an internal combustion engine built to run on liquefied petroleum gas (LPG) as a fuel.The Elantra PLI is a mild hybrid and the first hybrid to adopt advanced lithium polymer (Li–Poly) batteries.