One thing's for sure, General Motors is not very good at playing the real estate market. Last May the world's biggest automaker finally bought its world headquarters in downtown Detroit called the Renaissance Center for the sum of $626 million. It had initially bought into the complex of seven buildings back in 1996 for $75 million, but had continued leasing office space there until the purchase earlier this year. Here we are not five months later after the purchase and GM is reportedly considering selling the RenCen to raise $500 million fast.