There is no need for that many vehicles, but its still cool to have.
Sounds like the Ranger and Mustang are vehciles he wanted, so he got. A 4x4 and a fun car. The F150 was his dads, is paid off, and is nice to have around, and his mom mostly drives the Fusion...from the sounds of it. So its not outrageous to have the vehicles he has. Hell, I know people with 20+ vehicles. Half of them are projects, because thats their favorite hobby.