GMC Sierra 2006 Automatic Gasoline mileage: 300 KM or more Peace be upon you ! Looking for ! A Sierra from 2003 to 2006 Mileage under 450,000 Engine and transmission are guaranteed. Important things like consumables are normal or have very minor issues. Chassis is guaranteed. The body doesn't matter. The most important thing is electric windows. The transmission is the most important thing, fundamentally it doesn't matter if it's automatic or manual.