Fuel Workshop is one of the unreleased buildings on FarmVille that makes Fuel. It appeared in the Market for 1,000,000 coins to see how large the demand would be for it. On clicking buy, the user wouldn't actually get the Fuel Workshop (it was more of a test buy if it were to exist), and after clicking buy, the workshop would disappear and the coins would not be charged.
Note: This building was part of a pre-release test to judge the demand for crafting buildings. Prior to this test there was no suggestion that all crafting buildings would generate fuel, rather that each would generate their own peculiar set of power ups. While the exact sequence of events is not known outside Zynga, it is probable that the result of the test was that most people wanted fuel, and consequently the crafting system was reworked to eliminate this building and make fuel the ultimate product of the other three buildings.