Your truck seems to have the right numbers. 13city 17 highway 15 combined?
Did you know that the EPA has been doing different kinds of testing for cars since 2008. They have also adjusted older cars' mpg since then. They've been doing that to reflect on the higher population of drivers out there, as well as higher speeds during their commute.
My Matrix was rated at 30/36 but in reality it is only rated at 26/33.
If you send me a link to the page on the EPA site that has the numbers for your truck, I can update them.
The EPA doesn't make their new numbers available in a data format that we can use. So we can't update our listings across the board for every model. But if you send me that link for your model so I can verify the change, I can get it updated.