I heard the stories that rental trucks are detuned for reliability.
Years ago I was using F450 with 7.3l/230 HP engine for pulling 15k trailer. When the differential blow, I rented F550 with 6l engine that is rated at 320 HP. After hooking my trailer I almost created accident as F550 with auto transmission would barely move the trailer at the intersection, where F450 with manual would move without a problem.
Part of the problem might be auto v/s manual transmission, but I made topic on Ford Truck Forum and lot of member come with the story that rental companies detune the engines, as in rental truck we tend to brush redline more often than we do in our own.
