The Liberty is available in three trim levels: Sport, Renegade, and Limited Edition. Each is offered with two-wheel drive or four-wheel drive. The standard engine in all Liberty models is a 3.7-liter V6. A six-speed manual transmission is standard in Sport and Renegade. A four-speed automatic is optional on those models and standard on Limited. Optional on Sport 4WD and Limited 4WD is a 2.8-liter four-cylinder turbo-diesel that comes with a five-speed automatic. Liberty diesels also come with a bigger battery, P225/75 tires, 16x7-inch aluminum wheels, and an engine block heater. Standard on all 4WD models is Command-Trac, a conventional part-time four-wheel-drive system with a two-speed transfer case. Full-time Selec-Trac is optional on all three trim levels, and retains a low range for serious off-roading.For 2006, all Jeep Liberty models come with Jeep's Electronic Stability Program, anti-lock brakes, Electronic Roll Mitigation, and all-speed traction control.