If your car or truck were broken into by a thief, what is the most valuable thing they could steal?

I never leave valuables in the car for that reason.
useful habit - never tempt a thief

Radio/Cd Player/iPod Access
even though faceplate is removed
and the CD Collection...
    That's in the cab.
It's a Truck with truck box for tools etc.
They just broke into and took 
a couple of expensive tools, 
now both sides have double locks.

Nothing. All I have is my insurance card, registration, some small note pads, and a few cheap pens. I take the face of my car stereo off every time I exti my vehicle. I don’t leave anything valuable in it. 

My dash cam probably. It probably won't be so obvious because it's hiding in the mirror so maybe they won't notice it?

  Please don't remind me; even though it's been years and years since it happened, the pain is still fresh. I learned the hard way never to leave my satchel of tildes in the car . . . 

~

Change. 
DVDs. 
Car Seats
Worst would be a check book....I would have to stop pay on the book. $36.00

the seats