Driving at 55 mph as opposed to 65 mph can increase your fuel economy by as much as

Currently, the average diesel fuel efficiency for tractor trailers is 6.5 miles per gallon. Fuel economy can rise by as much as one mile per gallon while traveling at 55 mph as opposed to 65 mph. For every 100 miles traveled, that equates to a fuel savings of around two gallons., which can result in considerable financial savings over the course of a driving year.