Guys when doing your 3miler .... have you tried running it outside like its done @ prmc?? i.e The first 1.5 miles out in 12mins 30 and then the last 1.5 mile best effort ??? At least it'll give youa rough idea of how you'll preform and give you a rough guide on how to work at getting your time better! Throw in some interval/sprint work with your runs, that should help.
I've never timed myself on a three miler. Been doing a few test's on the treadmill for my PJFT but thats it. Getting just over 9.30mins. Done it a couple of times outside too and got roughly the same. Is a lot different outside, harder!!
I think its harder outside to, not just because of resistance and wind etc but also because its up to yourself to set the pace and not the machine! Runnin on the treadmill is easier on the joints though!
Treadmill is basically doing the work for you as the ground is moving for you so if you stop your obviously *text deleted* fall off, where as outside the only thing propelling you forward is yourself and if you slow down or stop then it's a bit different.
Although i find treadmills hard to run on as i get shin splints from them nearly every time i run on them :S