My parents have a 1998 Ford ranger extended cab, 2.5L 4 cylinder, 5 speed, worst vehicle I've ever driven! and I just got a call last night from a friend who was driving her husbands 1999 Ford Ranger regular cab and was asking if I had advice on how to talk him in to selling it.
Our ranger gets 12-18mpg doing mostly short in town trips, it's used only for hauling bulky stuff, we are debating selling it and buying a micro truck to replace it, even with new all season tires on the rear and sand bags in the back I've gotten it stuck so many times that I've lost count, the engine is also one of the most difficult I've ever seen to work on, it takes you all after noon to change spark plugs.
We bought it for similar reasons "to have a truck" after our '93 Toyota died with 335,000 miles, turns out it would have been worth fixing the Toyota.
I hope you are teaching your son to be responsible, by at least having him pay for insurance on the vehicle he drives, when I got my first vehicle my parents wouldn't even co-sign to let me get cheaper insurance, and if I barrow the truck it's expected that it will get returned with a full tank of gas.
We ended up with an '03 Ranger extended cab, 5 speed V6. Really hard to find a 5 speed, for some reason....tons of automatics though. Doing pretty well with it so far, haven't really crunched any numbers for FE, except drive home...got 24MPG on that trip.
Our son is responsible for maintenance on the PU, will be paying at least part of the bill, when he gets a job this summer. It's about impossible for him to work during the school year and keep decent grades. Unfortunately, he inherited my lack of interest in good grades at school.