For 2009, the 5-passenger Hummer H3 gets standard hill-start assist, which prevents the car from rolling on a hill when a gradient is detected and then holds the car stationary for two seconds, after the brake is released, to give the driver time to apply the throttle. Also available is a driver-selectable full-locking front differential as part of the Off-Road Adventure package. The 4WD 2009 Hummer H3 is equipped with a 3.7L inline five-cylinder that generates 239 hp and 241 lb-ft of torque with a standard five-speed manual transmission or optional four-speed automatic. EPA-estimated fuel economy is rated at 14 mpg city/18 mpg hwy and 15 mpg combined with either transmission. The H3 Alpha boasts a 5.3L V8 engine generating 300 hp and 320 lb-ft torque, paired with a four-speed automatic transmission, while estimated fuel mileage drops to 13 mpg city/16 mpg hwy and 14 mpg combined. Standard Hummer H3 safety features include antilock disc brakes, stability and traction control and full-length side curtain airbags.