The Trilobite app is very good for recording notes on locations and your tracks, but please do not rely on it as the sole system for locating yourself or your vehicle. Phones can fail, get damaged, or run out of battery.
Develop your bush skills, be observant of your surrounds at all times, and if in very remote country (and often featureless country) consider if you should be using a system like SPOT or carrying an EPIRB.
And make a habit of recording the location of your vehicle as soon as you park it.