There is currently no widely accepted accelerated test used by the automotive industry to evaluate perforation (inside-out) corrosion. Historically, automotive companies have used Proving Ground evaluations of full vehicles to assess perforation corrosion. Such tests are expensive, do not lend themselves to comparative testing of a large matrix of materials or processes, and are not available to supplier companies.The Perforation Subcommittee of SAE ACAP Division 3 has initiated a project to obtain perforation corrosion data from on-vehicle exposures that will lead to the development of appropriate laboratory perforation corrosion tests. The first phase is the development of a test specimen and methods to evaluate corrosion on this specimen. The proposed specimen is a two-panel assembly having an un-painted test area separated by a gap distance of .25 mm. This paper details the results of a corrosion evaluation of the effect of a number of design factors for the proposed coupon assembly.