GMC Sierra 2013 Automatic Gasoline mileage: 300 KM or more 4WD GMC Sierra 2013, double (4x4), 6-speed transmission. The car is clean, the body is clean, the chassis is guaranteed, airbags are guaranteed, and the AC is like ice. The interior needs installation, but the parts are available. Modifications done to it: Borla cat-back with Y-pipe and muffler delete, Bilstein shocks, King springs, Borla muffler, and a 40,000 BTU transmission cooler. Lowered 2 inches without cutting the chassis.