I would recommend a seat belt specific cutting rescue knife rather than a fixed blade carried accessible to the driver. I carry a fixed blade in my trunk kit. I also carry a spring loaded window punch in each car.

I have a Jack Emergency knife that I carry in each car. Great for seat belts, clothing etc. The recent post about the Benchmade rescue hook is also a good possibility and carries easily on the belt.

You can see the Jack and several other purpose built emergency knives at Paragear.

http://www.paragear.com/frame.asp?menu=g...p%3fgroup%3d388