Diesel prices remain mostly stagnant by admin | Sep 26, 2017 The average price of a gallon of on-highway diesel went down three-tenths of a cent to $2.788 per gallon for the week ending Monday, Sept. 25. This marks the second consecutive decrease after three weeks of increases. Powered by WPeMatico Share this:Tweet Related Submit a Comment Cancel reply Your email address will not be published. Required fields are marked *Comment Name * Email * Website Notify me of follow-up comments by email. Notify me of new posts by email.