Gross Output includes the market value of all intermediate capital goods produced during a given time period in addition to the items in GDP. So, not only the market value of automobiles sold to consumers, which is in GDP, but the market value of the iron mined, the steel made, the tires fabricated, etc. are in GO.
http://www.bea.gov/faq/index.cfm?faq_id=1034
Here is Mark Skousen on GO:
http://mskousen.com/category/gross-output/
