New/Used Contract Hire deals

Hi there can any of you guys tell me that are running their trucks on rural roads 90% of the time get on mpg , as most of our work is and we are averaging 6.8mpg on a mixed fleet at 40 ton and less I sometimes think there is better to be had , although it’s nice to see guys posting 9 /10 /11 mpg I’m sure a lot of motorway running is involved , I’m looking an opinion on work similar to mine .