A two‑dimensional finite element model that simulates multispecies, density‑dependent vapor flow and transport. Vapor2D was modified to predict the migration of gasoline vapors from a subsurface spill area, and includes a multicomponent NAPL source model. Vapor2D was successfully validated by simulating laboratory experiments of vapor flow and transport of heptane in the vadose zone, and Vapor2D has been used to assess density‑dependent landfill gas, chlorinated solvent vapor migration at field sites. The principle application of Vapor2D is the evaluation of landfill gas influence on groundwater quality. Vapor2D is a proprietary computer model.