The HHR was introduced in 2006 and for 2007 remains relatively unchanged. There are three trim levels for this five-door retro-cruiser that is styled to replicate a 1949 Suburban. The LS and LT1 model comes equipped with the 2.4Liter Ecotec four-cylinder engine that produces 149HP. Move up to the LT2 and you get a the same 2.4Liter engine with 16 valves that increases the horsepower to 172. A five-speed manual transmission is standard with a four-speed automatic optional.