May 21, 1999
                                
      Document Released for Stakeholder Review and Comment
                                
 Comparison of MOBILE6 Basic Emission Rates for 1981-1993 Model
    Year Light-Duty Cars and Trucks with FTP and IM240 Data
                                
                 Report Number EPA420-P-99-021

The Office of Mobile Sources, Assessment and Modeling Division,
announces the release of "Comparison of MOBILE6 Basic Emission
Rates for 1981-1993 Model Year Light-Duty Cars and Trucks with
FTP and IM240 Data" for stakeholder review and comment. This
document, also known as M6.EXH.010, is available at the MOBILE6
section of the OMS Web Site (http://www.epa.gov/oms/m6.htm).

The basic emission rates for 1981-1993 model year light-duty cars
and trucks were developed using both FTP and Ohio IM240 data.
This document derives alternative estimates using Colorado IM240
data in place of the Ohio IM240 data in an attempt to validate
the results obtained with the Ohio data, and provides a
comparison of the results. The document also provides a
comparison of the basic emission rates proposed for use in
MOBILE6 with available FTP and IM240 data.

Comments on this report and its proposed use in MOBILE6 should be
sent to the attention of Phil Enns. Comments may be submitted
electronically to mobile@epa.gov, by fax to (734)214-4939, or by
mail to MOBILE6 Review Comments, US EPA Assessment and Modeling
Division, 2000 Traverwood Drive, Ann Arbor MI  48105. Electronic
submission of comments is preferred. In your comments, please
note clearly the document that you are commenting on including
the report title and the code number listed. Please be sure to
include your name, address, affiliation, and any other pertinent
information.

This document is being released and posted on May 21, 1999.
Comments will be accepted for sixty (60) days. EPA will then
review and consider all comments received, and will provide a
summary of those comments and how we are responding to them in
the form of a followup document.

Thank you for your continuing interest in the development of
MOBILE6.

                           Sincerely,
                                
   Emission Inventory Group, Assessment and Modeling Division
                US EPA Office of Mobile Sources