[CREWZIN]

Eric,

The fuel filter is attached to the fuel pump and the gas tank has to be dropped or at least taken half way down to get to it. Most of us go for a lifetime (100,000+ miles) before even thinking about changing it. Unless you friend knows for certain that he's come into contact with some bad gas that might had clogged the filter, I don't think that's his problem.

A good tune-up, inflating the tires to a couple pounds above what's recommend and a change of habit on the way he drives with a light foot on the accelerator are the best ways to improve mileage.