"Denny" wrote in message ups.com...

Paper material in the bed of my truck at 55mph rotates once or trwice
in that standing vortex then vanishes over the tailgate - never to be
seen again...
Any empty, plastic gas can left against the tailgate slides up against
the back of the cab - again that standing vortex...
Now, that the gate up has less drag overal still amazes me, in spite
of knowing what is theoretically happening...

denny


I forget which brand truck we were looking at (Ford?), but it had a sculpted shape to the top of the tailgate about 8"
wide. The salesman said it helped to improve gas mileage...