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Modeling and Inventories

National Mobile Inventory Model (NMIM)

The National Mobile Inventory Model (NMIM) is a free, desktop computer application developed by EPA to help you develop estimates of current and future emission inventories for on-road motor vehicles and nonroad equipment. NMIM uses current versions of MOBILE6 and NONROAD to calculate emission inventories. Note, MOBILE6, used in NMIM, has been replaced by MOVES as EPA’s official model for estimating emissions from cars, trucks and motorcycles.  Thus, NMIM cannot be used for official modeling of these emissions. 

For Information about MOVES, including policy guidance on when it must be used for State Implementation Plans and transportation conformity determinations, click here

Because of the large amount of computing necessary to calculate a national inventory, the NMIM model is designed to utilize multiple computers over a computer network. NMIM will also work on a single computer, but much more slowly. The installation instructions describe minimum system requirements and how to install the software. The installation process is the same regardless of whether you are installing NMIM to run on a single PC or to use it on multiple PCs on a network. If you plan to use a network, however, you must install the software separately on each PC.

To request a CD of this software instead of downloading it or if you have trouble with accessibility of this software, please contact us for help.

For updates and news on EPA mobile source emission models, subscribe to the EPA-MOBILENEWS listserver: Subscription Information.

NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.

NMIM2008 Software & Documentation

  • System Requirements and Instructions for Installing the NMIM Software
  • Download the NMIM Installer (ZIP file, 350MB), NMIMInstall20090720.zip. This file includes the NMIM2008 software (version NMIM20090504), the NMIM County Database (version NCD20090531), MOBILE6.2.03, and NONROAD2008a (July 2009 version). This file may take 15 to 90 minutes to download with a high-speed connection. The file you download, NMIMInstall20090720.zip, should be exactly 359,039,213 bytes, which you can check by right clicking on the file, selecting Properties, and looking at "Size." If it is not this size, please try downloading it again. Large downloads work best when you are not attempting to run other applications on your computer and when traffic on your network is low. (Free zip software is available at www.download.com Exit EPA disclaimer)
  • NMIM User Guide (PDF) (75 pp, 1.8MB, EPA420-B-09-015), also available via the NMIM HELP menu, provides detailed information on how to run NMIM.
  • How NMIM Works: EPA's National Mobile Inventory Model (NMIM), A Consolidated Emissions Modeling System for MOBILE6 and NONROAD (PDF) (26 pp, 325K, EPA420-R-05-024, December 2005). This documentation begins with an overall explanation of how NMIM works, followed by the details of how it runs MOBILE6 and NONROAD. Next, it discusses the pollutant and source category inventories available from running NMIM. Then, it describes the NMIM County Database (NCD) and procedures for updating and improving it through the National Emission Inventory (NEI) process. Next, it explains how NMIM estimates various air toxic pollutants that are not direct outputs of MOBILE6 and NONROAD. Finally, it describes how user-specified retrofit programs and fleets are modeled by NMIM.

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