The HHR is available in three trim levels: LS, LT and SS. A 149 hp 2.2-liter four-cylinder engine and five-speed manual transmission are standard on LS and LT trims; a 172 hp 2.4-liter four-cylinder engine is also available for the LT. The performance-oriented SS trim gets a 260 hp 2.0-liter turbocharged four-cylinder engine with direct fuel injection, mated to a five-speed manual transmission. A four-speed automatic transmission is optional on all trims. Daytime running lights, driver and front passenger air bags, air conditioning, single-disc CD player and a tire pressure monitoring system are standard on all HHR trims; LT models add alloy wheels, a power driver's seat and MP3 capability. An optional 2LT package further equips the LT with features that include a sport-tuned suspension, upgraded wheels, fog lights, stability/traction control and 4-wheel antilock brakes; these features are standard on the SS trim. A more aggressive exterior styling, polished 18-inch forged alloy wheels, a performance driver's seat and unique upholstery are exclusive to the HHR SS. For 2008, a higher performance, turbocharged Chevrolet HHR SS model debuts. The LS and LT models carry over from 2007 with minimal changes.