Night Vision in cars can be great as it allows you to more easily spot people who are not easily seen in the dark. BMW is one user of this type of product in their 5, 6 and 7 series cars. FLIR have created a new product called the PathFindIR which is a thermal imaging camera designed for cars. It allows you to see past what your headlights will naturally light up and also spots the darker parts of the road that are difficult to see. Temperature is also detectable with this camera as it shows cold as black and warm as white.
A good example of the type of vision you will gain is below. As you can see, the person can clearly be seen with the camera but cannot with out it.
The way you see the image is by an LCD screen in your dash board although I have heard of similar solutions in the past which project the image on to your windscreen.
Although it is a little pricey at $4425 at the moment it is still beginning stages and as this item becomes more popular we should start seeing it become standard in cars.
Video Demonstration found Here.