I am about to buy a new truck. I have a 40 minute commute to and from work 5 days a week. I tow my 14' bass boat only about 30 or so times a year. I have to think about fuel mileage on an everyday basis.

I am looking at Ford Rangers. Does anyone have any experience towing a small boat with a 4 cyl?

A 14' boat you could haul with anything you buy, it need not be a truck.  I pull my 17' BassTracker with my Chevy Uplander van with ease.  I love the van it gets 25-26 mpg on the highway and 21 around town and I have all the room I need to carry my rods and tackle and the ability to lock them up inside if I am leaving it setting in a parking lot.   Of course I say this while I own 2 trucks that I can use to pull the boat if going to a questionable ramp.

I used to pull my 17 foot Bass Tracker with a four cylinder Mazda B2500 which is the same as a Ranger.  You will have no trouble at all.