cknsls@adelphia
New member
ACCORDING TO THIS ARTICLE - they don't increase miles per gallon:
http://www.detnews.com/apps/pbcs.dll/article?AID=/20071017/AUTO03/710170429/1149/AUTO03
http://www.detnews.com/apps/pbcs.dll/article?AID=/20071017/AUTO03/710170429/1149/AUTO03