Many dash cameras include motion detection, but the problem is that they need to be powered – which normally includes the display energised. In reality, motion detection limits the recording to when there is some movement within the video frame (rather than continuous).
This camera looks like it might do what you want, mostly because it does not have a built in display – so can be set to motion detect, without the miscreant knowing that they are being recorded.
However, its low light level performance is not specified; before purchase I’d recommend that you ask the seller what light level it will operate at (ideally it should be 0.1 Lux or better).
It is not clear how the unit is connected to the 12V vehicle supply, it may require hard wiring via a fuse if it does not use a cigar lighter power connection.
Don’t expect any help from the police, even if you can identify those causing the damage, it’s too much trouble for the police to investigate such criminal damage.
http://www.ebay.co.uk/itm/DashCam-Mini-HD-720P-Dash-Cam-DVR-Video-Recorder-120-Lens-G-Sensor-Motion-Detect-/201184030826?pt=LH_DefaultDomain_3&hash=item2ed780b06a