GMC Sierra Z71 2013 Automatic Gasoline mileage: 300 KM or more Mashallah, GMC Sierra 2013. Original body. Full option Z71. Rotary 4WD. It has a 6.0 engine, stage 2 camshaft, LS3 823 heads. AEM wideband, XREVOLUTION sports gauge. 40,000 BTU transmission cooler, sports thermostat, sports fuel pump. Tuned by Safety and Tuning (no rev limiter). There is a minor dent in the bed, shown in the picture, and a minor issue with the interior. The rest is 100% sound.