Auctions generally do not lead to efficient outcomes when the value of the object for sale depends on both private and common value information. The resulting inefficiencies may and common value information. The resulting inefficiencies may get magnified if bidders fall prey to a winner's curse by putting too much weight on their common value information. We report a series of first-price auction experiments to test three key predictions of auctions with private and common value elements: (i) inefficiencies grow with the uncertainty about the common value while revenues fall, (ii) increased competition results in more efficient outcomes and higher revenues, (iii) as does public disclosure of information about the common value. We compare the predictions of several bidding models, including Nash, when examining these issues. A model in which a fraction of the bidders fall prey to a winner's curse and decision-making is noisy, best describes bidding behavior. We find that revenues and efficiency are positively affected by increased competition and a reduction in uncertainty about the common value. Public information about the common value also has positive effects on revenues and efficiency, although less so than predicted by Nash equilibrium bidding. When the quality of the public information is increased, its effect on efficiency and revenues becomes more pronounced.