I don't quite get the IR claim either, as you tend to drive with headlights on which would white-out the IR.
I did try it on the driveway with no headlights, but couldn't see anything, screen certainly didn't go all grayscale.
I will see if I can post some of the Portugal trip I recorded on mine, it's nice and clear, for normal use its ok. In relation to the accident, its absolutely spot-on, completely clear, up to about 7m, after which some detail is lost, but as accidents tend to be less than 7m (otherwise wouldn't be accidents!) it's good enough for my needs.
This is the very cheapest though, there is another tube-like one at about £30, or you could buy a pukka one for £100 - £200, horses for courses really.
Picture quality aside, I'm far happier with it in place.
Cheers
Pete