2007 Nissan Quest fuel system problems

The stated mpg for my 2007 nissan quest on the window sticker shows 18 - 24 miles per gallon yet after 10 months the van only gets 17.6 miles per gallon and that is during mostly highway driving. When questioning this a dealership after waiting a few months to see if any improvement we where advised by the salesmen what did we expect for a v6 lsrge vehicle. I do not understand how they can be allowed to show higher mpg on a window sticker then what the vehicle actual gets.

Same as most others on here, we were driving and the vehicle ran out of gas. Gas gauge read just over quarter of a tank, yet was actually empty. We do our best to get it filled up at a half tank, but this is the third time this has happened in a year and a half. We've gotten two letters from nissan informing us of the issue, but it's starting to appear as though nothing is going to be done to fix this safety issue. Hopefully someone doesn't have to die to get them to stand behind their product.