The 'sense' or ability of knowing where the physical boundary of your automobile is at all times, especially when driving through narrow alleys or parallel parking - the ability that allows you to avoid parking by Braille. If you think of your car as a convex hull surrounding you, then propriocarception is the ability to know (or sense, if you will) when that convex hull is about to contact something other than the road, and thus avoid it. Luke Skywalker demonstrates Force-boosted amazing levels of propriocarception when flying the Trench on the first Death Star; Lando Calrissian demonstrates a failure of it when he torques the upper dish antenna off the Millennium Falcon while flying through the superstructure of the second Death Star in Return of the Jedi.

The corners of my bumpers indicate that my propriocarceptive quotient isn't too damn high.