Should You Modify to Improve Fuel Mileage?

A good number of the people I talk to who drive trucks are thinking about modifying their vehicles in some way to improve fuel mileage. The topic heats up every time gas and diesel take an upward hike or don't trend downwards after staying at what we consider to be the high side for awhile. I've made a few modifications to my truck, but additional changes haven't seemed practical when I compared the expense of doing it vs. the benefits the modifications would provide (uncertain fuel prices might make me rethink that decision). If your motivation is environmental, and expense isn't a factor, you probably want to make any modifications you can to get better mileage. But if your intent is solely to save money, consider your driving habits and a few other factors before loading up the truck with fuel-saving accessories. Do the math.