Diesel prices maintain a slight downward trajectory by admin | Dec 12, 2017 The average price of a gallon of on-highway diesel went down 1.2 cents to $2.91 per gallon for the week ending Monday, Dec. 11. This marks the second consecutive decrease after a short-lived increase two weeks ago. Powered by WPeMatico Share this:Tweet Related Submit a Comment Cancel reply Your email address will not be published.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.