Back in my highschool days a friend of mine's dad had a beautiful '66 chevy 4x4 pickup. It was his pride and joy, his dad bought it new and handed it down to him, and it was in perfect shape...
One morning my dad and I are on our way to school when we see this seafoam green machine barreling out of the quik-e-mart parking lot in reverse and hauling ass down the road. We swerve and narrowly miss getting hit, but the city cop behind us wasn't as lucky. The truck nailed the copper car dead on the front drivers side fender, went halfway up the hood and blew the windshield out.
Chasing this '66 chevy was my friend's dad, he dropped his pack of donuts and coffee midway down the parking lot, but of course there was no catching that thing...
dad and I stopped and got out, come to find out the parking brake on this '66 chevy had been out of adjustment for a while, and he stopped at the quik-e-mart every morning to get coffee, and left the truck running to warm up, but today his usual parking spot was taken, so he parked in a different spot on a very, very slight incline - Force of habit dictates he left the engine running as usual.
Truck was banged up pretty good, the city cop was damn pissed, and my friend's dad went to work that day with a banged up truck, a nice ticket, no coffee or donuts, and badly damaged pride...
All this being said, the parking brake in my truck hasn't worked since I bought it. I never leave it running, always slam it into first gear. If I am on a hill I wedge something under the tires. This experience taught me that even a very, very slight incline gets things into motion, gravity and inertia take it from there...
