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Evaluation of Rear Window Defrosting and Defogging Systems; Technical Report

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National Highway Traffic Safety Administration (NHTSA), Department of Transportation.


Request for comments on technical report.


This notice announces NHTSA's publication of a technical Start Printed Page 20666report evaluating rear window defrosting and defogging systems. The report's title is Evaluation of Rear Window Defrosting and Defogging Systems.


Comments must be received no later than August 16, 2004.


Report: The report is available on the Internet for viewing on line in HTML format at​cars/​rules/​regrev/​Evaluate/​rearwindow-report/​index.htm and in PDF format at​cars/​rules/​regrev/​Evaluate/​rearwindow-report/​rearwindowreport.pdf. You may also obtain a copy of the report free of charge by sending a self-addressed mailing label to Christina Morgan (NPO-321), National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590.

Comments: You may submit comments [identified by DOT DMS Docket Number NHTSA-2004-17525] by any of the following methods:

  • Web site: Follow the instructions for submitting comments on the DOT electronic docket site.
  • Fax: 1-202-493-2251.
  • Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590-001.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal Holidays.
  • Federal eRulemaking Portal: Go to Follow the online instructions for submitting comments.

You may call Docket Management at 202-366-9324 and visit the Docket from 10 a.m. to 5 p.m., Monday through Friday.

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Christina Morgan, Evaluation Division, NPO-321, Office of Planning, Evaluation and Budget, National Highway Traffic Safety Administration, Room 5208, 400 Seventh Street, SW., Washington, DC 20590. Telephone: 202-366-2562. FAX: 202-366-2559. E-mail:

For information about NHTSA's evaluations of the effectiveness of existing regulations and programs: Visit the NHTSA Web site at and click “Regulations & Standards” underneath “Vehicle & Equipment Information” on the home page; then click “Regulatory Evaluation” on the “Regulations & Standards” page.

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Rear window defrosting and defogging systems are not required on motor vehicles by any Federal standard. However, NHTSA from time to time evaluates technologies that are widely available on production vehicles and might have an impact on safety. Rear window defoggers became available as optional or standard equipment in most cars during the 1970's or 1980's and are popular with consumers. Today, almost all passenger cars, minivans, and sport utility vehicles have rear window defoggers, but most pickup trucks and full-size vans do not.

The analysis examined whether there were proportionately fewer backing-up and changing-lane crashes involving cars with rear-window defoggers than cars without rear-window defoggers. The database was extracted from State crash files. The analyses did not show a benefit for rear window defoggers. The main analysis found that rear window defoggers have no effect on changing lane and backing crashes in conditions when they are most likely used (when raining or snowing, during the earlier part of the morning, or during winter).

Even though this study did not show a tangible safety benefit, it is understandable that rear window defoggers are well received by consumers because they conveniently clear condensation, frost, ice, and/or snow from the back window.

How Can I Influence NHTSA's Thinking on This Subject?

NHTSA welcomes public review of the technical report and invites reviewers to submit comments about the data and the statistical methods used in the analyses. NHTSA will submit to the Docket a response to the comments and, if appropriate, additional analyses that supplement or revise the technical report.

How Do I Prepare and Submit Comments?

Your comments must be written and in English. To ensure that your comments are correctly filed in the Docket, please include the Docket number of this document (NHTSA-2004-17525) in your comments.

Your primary comments must not be more than 15 pages long (49 CFR 553.21). However, you may attach additional documents to your primary comments. There is no limit on the length of the attachments.

Please send two paper copies of your comments to Docket Management, submit them electronically, fax them, or use the Federal eRulemaking Portal. The mailing address is U. S. Department of Transportation Docket Management, Room PL-401, 400 Seventh Street, SW., Washington, DC 20590. If you submit your comments electronically, log onto the Dockets Management System Web site at and click on “Help” to obtain instructions. The fax number is 1-202-493-2251. To use the Federal eRulemaking Portal, go to and follow the online instructions for submitting comments.

We also request, but do not require you to send a copy to Christina Morgan, Evaluation Division, NPO-321, National Highway Traffic Safety Administration, Room 5208, 400 Seventh Street, SW., Washington, DC 20590 (alternatively, FAX to 202-366-2559 or e-mail to She can check if your comments have been received at the Docket and she can expedite their review by NHTSA.

How Can I Be Sure That My Comments Were Received?

If you wish Docket Management to notify you upon its receipt of your comments, enclose a self-addressed, stamped postcard in the envelope containing your comments. Upon receiving your comments, Docket Management will return the postcard by mail.

How Do I Submit Confidential Business Information?

If you wish to submit any information under a claim of confidentiality, send three copies of your complete submission, including the information you claim to be confidential business information, to the Chief Counsel, NCC-01, National Highway Traffic Safety Administration, Room 5219, 400 Seventh Street, SW., Washington, DC 20590. Include a cover letter supplying the information specified in our confidential business information regulation (49 CFR part 512).

In addition, send two copies from which you have deleted the claimed confidential business information to Docket Management, Room PL-401, 400 Seventh Street, SW., Washington, DC 20590, or submit them electronically.

Will the Agency Consider Late Comments?

In our response, we will consider all comments that Docket Management receives before the close of business on the comment closing date indicated above under DATES. To the extent possible, we will also consider comments that Docket Management receives after that date.

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Please note that even after the comment closing date, we will continue to file relevant information in the Docket as it becomes available. Further, some people may submit late comments. Accordingly, we recommend that you periodically check the Docket for new material.

How Can I Read the Comments Submitted by Other People?

You may read the comments by visiting Docket Management in person at Room PL-401, 400 Seventh Street, SW., Washington, DC from 10 a.m. to 5 p.m., Monday through Friday.

You may also see the comments on the Internet by taking the following steps:

A. Go to the Docket Management System (DMS) Web page of the Department of Transportation (

B. On that page, click on “Simple Search.”

C. On the next page (​search/​searchFormSimple.cfm/​) type in the five-digit Docket number shown at the beginning of this Notice (17525). Click on “Search.”

D. On the next page, which contains Docket summary information for the Docket you selected, click on the desired comments. You may also download the comments.

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Authority: 49 U.S.C. 30111, 30168; delegation of authority at 49 CFR 1.50 and 501.8.

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James F. Simons,

Office Director for the Office of Regulatory Analysis and Evaluation.

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[FR Doc. 04-8632 Filed 4-15-04; 8:45 am]