Hmmm....Makes me glad we don't have GPS units in our vehicles. We still do our 'navigating' the old fashioned way. :)
Several years ago, we made the same horrible mistake, of leaving the truck unlocked one night at a large, resort campground near the beach. Even bigger mistake: DW left her purse sitting in the truck, on the seat in plain site. Talk about just BEGGING a thief to drop by and 'shop'!
Anyway, next morning, contents of DW's purse and the glove compartment were spread out all over the seat. A few items were on the ground outside the truck at our campsite as well.
Here's the kicker: They took NOTHING! They just rifled through everything and made a mess, found nothing worthy of taking, so moved on. Like most thieves, it was clear they were looking for something they could put their hands on quickly and easily, and turn over quickly for cash (jewelry, expensive electronics, or just cold hard cash). Since they found NONE of any of those in our truck, they just moved on.
Contacted campground security next morning, they came and did a report, etc. They informed us that several folks there had been 'hit' that night in similar fashion. Thieves got a portable DVD player from one family that made the horrible mistake of leaving such in an unlocked car. We learned from that and moved on. Now, we lock our car doors ANY time we leave the car, even if its just for a few minutes. And, we keep the stuff we know thieves target (stuff they can turn around quickly for cash) out of the car in our possession, or at least hidden as best we can.
Look at it on the bright side: At least, since you accidentally left the truck unlocked, you're not having to replace a window or door lock on the truck, as would be the case if they broke their way into your truck. :)