Compare to a first or second gen and get back to me.
It obviously won't be great compared to a car but as far as trucks go it shouldn't be that bad. My 2002 F-150 has pretty much the same shapes and whatnot, drags around another half a ton wrapped in a much bigger carcass and can still got close to 20mpg with a V8 and the tires that Ford put on it. Still gets 15-17mpg hwy with 32" mud tires. Same body as a newer Lighting but much taller, 4wd, extended cab and has a steel box. With the exception of everything being bigger it has the same crap under it in pretty much the same locations as a '98+ Ranger.
For the .49 it just says "Ranger". Well all know what a Lightning is but it isn't that fair to compare say... a Level II FX4 to a Lightning.
http://ecomodder.com/wiki/index.php/Vehicle_Coefficient_of_Drag_List